Overstock.com's deal is better. It's on sale for $18.99 (for PS2), and there's a free shipping code as well (check the overstock deal of the day thread for it).
There's still a chance that outpost would offer free shipping before the game is releeased, right?
My psp version is messed up or something, I've been stuck on the end of the second island since I got there and I keep forgetting to try a different copy.
Currently for overstock.com, you can follow a 10% off link from currentcodes.com that will knock 10% off ($1.90), and add code 85704 for free shipping bringing the total to $17.09 (tax only in Utah and Indiana)