The only RL situation I have that relates to this is the one and only time I ever bought a brand new car. The dealers priced it as a base spec model but it had somewhere in the region of £5-6k of extras. The salesman didn't realise and I signed up for it. Had the sales manager on the phone an hour later saying it had been priced wrongly and would I consider cancelling the agreement. Errrrrr, let me think about that for a second. No thanks! He didn't have much choice other than to find the person who put it up at the wrong price and whip them to within an inch of their lives. I didn't care though, stupid people are stupid. Lesson learnt hopefully.
If someone underprices currency then tough shit, I'd buy it in a heartbeat. There's no morals involved. I don't know why morals are even being mentioned. The only person who looks dumb is the fuckwit who is incapable of pricing their bazaar correctly and there's no two ways about it.
If you're dumb enough to underprice something then don't cry like a little girl when someone takes advantage of your stupidity. And going to your LS leader to get them to cry on your behalf too....that's just classy.