There is/was a guy locally who had a warehouse full of stuff including 40-50 bikes in a marginal neighborhood. I could never get a price out of him. It's like if he gives a price and I say okay then he figures he could have got more. As it ended he got nothing.
About the only thing one could do, if they have the funds, is to figure out what bikes you want at the most you'd pay for those, total those up, then take the total and divide it by the who lot including the junkers, then make him a one-time offer on all of it - take it or leave it. If he takes it then dump off the junk for $5 each.
But, yeah, sometimes the hassle ain't worth it.
Side story on auctions:
A few years ago there was an estate auction of several estates which included a lot of books. In most of the boxes there were a couple of books I wanted. There was also a re-seller in the audience. Every time I bid she'd bid more. After about five boxes I thought ("let the games begin"). Every box of books I'd bid on against her up to around $20, which is the most I wanted to get stuck at. If she had just let me have one box I would have been out and she could have got the rest for about $5/box. But, noooo, she wanted all of them, and wound up paying at least four times what she could have got them at, there were about 30-40 boxes of books. At the same auction I noticed someone else giving another bidder the same treatment on costume jewelry, the jewelry jumper wound up paying about eight times more than she would have if she just would have let others have some too (faund that out from the under-bidder after the auction). The auctioneers were happy though.