How much money can I get for a PSP?

I want the new Nintendo DSi and I was planning on selling my PSP (the oldest model) and some UMDs. It's in good shape with all the original packaging, a 1 GB memory stick, three games (MGS: Portable Ops, Castlevania: The Dracula X Chronicles, SSX Tricky) and three movies (Something About Mary, Snatch, Joe Dirt). How much should I get for all this and where would be the best place to sell it? (Game Stop, EB Games, etc)