O.K, so I bought Assassin's Creed II on January 2nd. Gamestop said about a few days after that date that the trade in value in is $22.50 cash, and $28.00 in store credit, which is pretty decent. I plan on beating Assassin's Creed II before BioShock 2 comes out, so I can trade it in and get BioShock, or at least a great discount, and then beat BioShock before Battlefield: Bad Company 2 comes out, and then play Battlefield until Bioshock 2's prices drop. Halo Reach and other games are going to fit in some time this year, but I haven't worked all that out yet. 
 
I have a feeling 2010 is going to be one great year for gaming.