picky system... or I'm doing something wrong but when I try to find Haze it won't find it.. not even motorstorm.
Quite possibly. I just did a search on a few games seeing if I could find a few nice trade-in values, and a majority of the games I searched had no results, or the results were completely unrelated games (Metroid Prime for instance isn't on there, though 2 and 3 are, but it shows No More Heroes and Okami). While I'm an enormous enthusiast of complete games, and Amazon does have the benefit of the marketplace being a better place to sell new/rare releases, taking ALL games and taking them with/without cover art/manual gives GS a nice boost.
They're roughly equal in my eyes considering you have to make sure the stuff is complete, though Amazon credit is tempting. I've been browsing looking for good GS to Amazon flips, but haven't really come up with anything. I'd make a thread but I'm not on here enough to update that thing.