Not going to happen.
The sites you should be checking are zzounds, guitarcenter.com, samash.com, and amazon.com. Also try using google product searches. A lot of local music shops will match the lowest cost you can find online and ship for free, so it may be a good idea to find the lowest online price, then show it to a local music price so you can get the online pricing without paying shipping.
What exactly are your goals for using this keyboard? Since you didn't want a midi controller, then I assume you're buying a piano to use as a musical instrument in the normal sense (as opposed to using it just for the sake of music production).
In this case, you want something as close to a real piano as possible. Obviously nothing can perfectly emulate an acoustic piano, but what you want to do is come as close as possible.
Don't go to craigslist. Buy a new instrument.
You may want to look under "digital pianos" instead of "keyboards" when shopping around online. A digital piano is just a keyboard specifically designed to feel and sound like a real piano. They typically have less instruments than a keyboard (digital pianos will have between 3-20 [though some have much more] whereas a keyboard will have every general midi sound (at
least 128 instruments, but typically up to 500+).
There's also another class of instruments separate from "digital piano" and "keyboards" called "music workstations". These cost thousands of dollars and have every sound a basic keyboard has plus much more. In addition, each of the sounds are typically very high quality (whereas keyboard sounds are usually very crappy). Workstations have other functionality such as mixing utilities (delay/reverb/etc) and sequencing functionality. Basically they have nearly any functionality and sound a music producer would need to create an entire song. Obviously this isn't what you're looking for, but I just want you to be aware of anything you'll run into while shopping around.
Even though digital pianos typically lack the quantity of sounds and some other features or basic keyboards, the piano sound of a digital is typically much higher in quality (the piano samples on a digital piano can be as great as those on a workstation). Also, digital pianos typically have weighted keys which are designed to come as close to the feel of a real piano as possible.
So if you want to come as close to a real piano as possible, digital piano is the way to go. I assume the amount you want to spend is low (based on your post).In my personal opinion, the best low end digital piano for its price is the casio privia. It will probably run you at least 400 dollars (which is very cheap for a digital piano). Of course, you do get what you pay for, but that's not to say the privia is a bad instrument. It wont be nearly as good for the $700~$1000 range piano, obviously, but it's one of the best deals in the 400~600 price range. It's much better than the William's Overture in my opinion.
Typically, if you find a casio and a yamaha at the same price, you'll want the yamaha (though I don't think you'll find one as low as the privia). Avoid M-Audio digital piano. Their midi controllers are awesome, but their digital piano sucks in my opinion. It's may be tempting since it is the absolute cheapest digital piano you'll ever find (one of them costs less than the privia), but it's really not worth it. I dont like the sound or feel of M-Audio's digital piano, and from what I hear, break easily. There's also a cheap Casio CDP, which is also cheaper than the privia and should also be avoided (again, I don't like the way it sounds or feels). Basically, you should be either paying the amount a privia costs, or buying something more expensive than a privia. Don't go for anything cheaper.
There's a Yamaha YPG-535 with 88 keys that is barely higher than the privia. I know I said yamaha is typically better than casio for a given price, but in this case, do not get the yamaha. It sounds great and all, but the keys are not fully weighted. They call it "soft touch" action, or something like that. I call it "not fully weighted so why bother?". Though it's sound is better than that of the privia.
The william's overture I mentioned earlier is also about the same price of the privia, and it is a pretty good piano for that price range. I prefer privia over the overture as a matter of personal taste. You can go to samash or the guitar center and try them both out yourself. You may like the Overture better.
The next tier of keyboards are in the $550/600~$1000. In my opinion, yamaha is the king of this price range. If you're spending this amount of money, the brand of keyboard you should come home with is a yamaha. The only debate should be which yamaha, not which brand of piano to buy. There are casios/korgs/rolands/williams/maudios in this range though, but I just prefer the yamahas for this range.
You wont see a *huge* jump in quality between the low tier pianos listed earlier (less than about 550), and the mid tiers (under 1000). So if it were me, I'd just buy something lower end, though if you have the cash, a 700 dollar yamaha is a pretty sweet instrument. Just make sure what you're buying is weighted (as opposed to soft touch, or semi-weighted, etc. Fully weighted or
)
Once you're paying in the thousands, pretty much every option is awesome. In this range you're going to be choosing between yamaha, korg, and roland. I don't know if casio has anything in this range, but if they do it probably isn't worth it. I'm a HUGE fan of the yamaha clavinova. The YDP series is pretty awesome too.
I think every digital piano you'll ever buy has midi capabilities. Some of them have USB capabilities, which is extremely convenient. If your digital piano doesn't have usb connections, then you'll need a midi to usb cable to connect to your computer (if you ever decide to). Just be aware of this while shopping around.
Side note: If you buy a privia, you'll want to buy a pedal too. The priva comes with the pedal, but the pedal it comes with is freakin retarded. It doesn't look or feel like a real pedal. In fact, if you're wearing shoes you can't even use the pedal (because the pedal is so weak that you can hardly tell if you're actually depressing the pedal or not). Get a basic M-audio pedal if you buy a casio privia.
Edit: Another side note: Some digital pianos are called "stage" pianos. This just means that instead of designing them to look as close to a real piano as possible, they've instead designed them to be more easily portable. But in terms of feel and sound, a digital stage piano is the same as a digital piano.
E.g: clavinova
Privia
The privia is basically a big box shaped thing that you can sit on top of a stand or something, so some may call it a stage piano due to the fact that it was designed to be portable.
Privia price
William's Overture (You can probably find it cheaper if you look around)
M-Audio Pedal
Piano Forums
Yamaha YDP series (cheapest of the series, I think)
Mid Range Yamaha Note that my definition of low/mid/high range is different than others. Some may consider anything less than 1000 as low 1000 dollars is nearly a tenth of what I make per year, so it's pretty high to me. I base my tiers more on the price ranges where I see noticeable changes in quality, though I guess that's somewhat subjective.
Edit: Also, another thing to look at when shopping around is polyphony. Polyphony is the maximum amount of notes you can play at the same time. If you go above this limit, you'll notice notes dropping out. Some people would suggest going as high as 64~128. I personally have never noticed a problem on instruments with only 32 note polyphony (though I suppose if you layer the sounds, you'll then only have 16 notes of polyphony, which will be problematic).
Don't forget, you can (and should) go to the music stores and try the pianos out by hand. You can also view demos of pretty much any instrument on youtube.
http://www.youtube.com/watch?v=6K4K-A65lxU
http://www.youtube.com/watch?v=cd16rm8u7oo
You
really need to hear one of these in person though. I could play one of these forever. Any youtube video doesn't do it justice. Not to say it didn't sound great on the video, I'm just saying you really need to play one of these yourself.
Also, he spends a lot of time on these videos showing other instruments. The only one I care about is the piano sound. In fact, all of my assessments made in this thread was based solely on the piano sound of the instrument and not on the other instrument sounds they come with.
If you type in any piano on youtube, you'll probably get some demo or review. You can also google the words and get demos from the website (e.g.
http://www.priviapiano.com/demonstrations/ As you can see, there are a few different types of privias. The px120 is the cheap one
http://www.williamspianos.com/products/overture.cfm has an overview of their instrument, but no demos).