EB Games is an evil place. This evil can be pinpointed: EB Games is a business, specifically a bricks and mortar retailer. And though all businesses are susceptible to many different kinds of evil, EB Games has a special kind of contempt for the other businesses it deals with before making so much as a sale to its customers. Specifically, the publishers and distributors that provide the games for them to sell.
EB Games has decided that instead of paying publishers the $50/60/70-odd (depending on the title, it's somewhere in that range) for a new release game and selling it for $100, it's cheaper to coax people to sell their games (read: trade in and save!) for $25, after which they're pushed onto anyone and everyone even remotely interested in a copy of the game for slightly less than the RRP of a new copy.