I've bought and sold a lot of things on GB. If I am looking for something, I filter out the "reserve" auctions. That cuts the choices considerably. Whenever I sell an item, I start the bids at the bare minimum I will accept for it, and let the auction run it's course.
I picked up a box of gun stuff at an estate sale a couple of years ago for $10. After identifying, photographing, and listing all the items, I cleared over $250.
Bargains can be found there, just be patient.