I have the firepower P90 it was my first gun I bought it for $49.95 at Forest City Surplus.
Its a decent gun for ROF and FPS. But the magazine is junk. It jams the gun up.
I was told though if you get a TM Mag it fits into the firepower gun. I've used it alot with .12 bbs but as soon as you put in .2+ bbs the mag doesn't push the bbs in. AKA Cheap highcap. SO if you get some Std TM P90 Mags your in better area. For the $50 or so that it is its not to bad for a little shooting but definetly not the best gun you can get.
Get a JG or a Cybergun I got the sig 552 bad ass gun IMO for the $200.