By that logic, it is not reasonable to say anyone ever paid too much for anything. Nobody ever gets ripped off on anything, since it is obviously worth what they were willing to pay. Really, he should have paid a million dollars for it; because then he'd have a bike worth a million dollars!

More seriously, it is common for inexperienced mechanics to assume that if they get a frame for some really cheap price that they are most of the way to a really cheap bike. This is not generally the case. Right now, for $15, patthepunk has some scrap metal. If he wants to make a fixed gear, he needs new wheels, seatpost, seat, chain, chainring, pedals. For the cost of all that, plus $15, he can have a heavy, not very nice fixed gear. You might well get all that cheapest if you buy them all together attached to a nicer frame than the Schwinn, by just buying a new bicycle.

Hmm.. I just looked at the pic of the other "Nothing fancy, all DIY" bike... freewheel, one brake, on the rear, with a suicide lever. So... suggestion for the Schwinn, sorry to be blunt: Don't DIY. You don't know what you're doing.