I've bought several off of archery talk and find it a very good way to save some money. Typically you can find the new releases for a couple hundred less a few month after the release dates. Be patient and you can find some exceptional deals
A 2 year old bow is a GREAT deal, especially if you want a flagship bow, and of course will kill just as many deer as it would when brand new.
Most flagship bows are now in the $1100 and up range bare bow. a 2 year old model will normally end up selling in the $600-$700 range and most of those will have some or all accessories on it. Bows in general never hold much resale value for some reason.
I sold a few recently on AT, set a price make offers don't go above your price I got a heck of a deal on this years deer rig. And it's a sweet shooting bow aswell.
I've never bought a used one, but most people who sell them don't really NEED a new bow. Most are perfectly fine, we all like new toys and we sometimes gotta get rid of the old ones to buy new ones.