I say use 400-500 to paint the bumpers and have the skirts cleared after doing the DIY grey removal, and use the other 500-600 on swaybars and a Xbrace. If you want more engine power, use the remainder on some pullies and cams, or an cheap exhaust setup.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>