yup, they have extensive classifieds... and usually priced pretty decent on the whole... but as with anything, best to be aware of what you're buying and from whom...
i've been lucky enough to get a couple of things 'used' -- with the help of bruce lanthier who really did all the work........almost new bow , range finder,etc - great gear.........as the guys have stated just know who or what you're dealing with!
I have bought three bows from E-bay and always had a good experience. I would try right here on BH.com, I have abow for sale here! I just bought an Elite Z28 off of E-bay.
AT for 95% of my buying and selling. If I'm buying, I just make sure the guy I'm dealing with has enough feedback to make me feel comfortable but I still ask alot of questions and I always pay with PayPal. I've had a few "iffy" deals over there, but never been just outright shafted.