Honestly, I this this as just dishonest bargaining. These people are trying to con you into a low price so they can save the money or else resell it. You did your research ahead of time, so you weren't taken advantage of.
While you are right, the bottom line is it's a free market...If you are dumb enough to try and sell something without doing research first, you deserve to be ripped off.
I don't think anyone deserves to be ripped off just because they did not spend a couple of hours on the net figuring out what something is worth. I'd love to see us move back towards a time when ethics ruled actions and away from the current 'if you can get away with it, it must be Ok' mentality.