I think any entry level system that will get you decently far into photography or at least get you a good start is going to run around $500-$600 just to give you a base price. From what I have seen this will get you an advanced point and shoot, good micro 4/3 setup or a Nikon or Canon entry level dslr kit.
Just wanted to add that to everything Kkel said. Also the 4 DSLR options he listed (2 for nikon and 2 for Canon) are what I would recommend checking out too. Make sure you hold them and play with them before purchasing though because ergonomics is really important in your comfort when using a camera.