It was years ago, most Gamestation shops don't even sell anything older than PS2/Xbox/Gamecube here now. The nearest Gamestation I've been to recently only had PS1 games in the "retro" section...
I take anything older than the current generation to one of the used stores near me. I can get fair cash or good trade if it isn't a random GTA, sports, or shooting game.
I know nothing about the psp, the console sucks imo.