Really it has no effect on you. You're just belly aching about something that isn't an issue. It's a 4 player co-op game. I hope you have at least 3 friends to play with. That way you don't have to play with a random who may have bought an item with money.

edit: Oh and the auction house is it's own game. I've spent a lot of time trading in game AHs and i find it to be pretty fun. I still don't get why it's an issue for you what other people do in their games. Reminds me of someone who is offended by what goes on between consenting adults in their own bedroom.