When I need the wheels of my bike looked at, I take them off the bike and to the LBS's here. They don't charge much to go over them. At least not here, and they'll even fiddle with them on the truing stand for a few seconds checking tensions and stuff while I wait and watch. If the wheel doesn't need much then they many times give them back to me free of charge. If one wheel needs some more in-depth looking at then it might cost me $15 - $20 when I get the other back in a day or two.
$400 a bike to destroy them will get expensive quick. While I don't know how it goes for them, when I ride in organized century rides there are quite a few heavy men and woman that speed past me in a paceline while I'm solo or a group of 3. They seem to be on nice mid range priced bikes in the $2000 range.
So if you are buying cheap used $400 bikes, I think there is a flaw in your thinking. If instead you are getting $0 bikes that you just put tires on, that's probably okay.