Some options in that budget would include stainless steel brake lines and/or upgrade pads (and maybe rotors). RS4 pedals run around $200 (I think the '08s already have that right?). Also a Stasis diff upgrade is $550 (plus install), a bit of a stretch. You might also be able to get an exhaust shop to do a custom exhaust in that price range (probably stretching it there too). You might be able to get different wheels, keeping the same tires. If you don't have a VAG-COM cable, that is a worthwhile investment. Lastly, Fly's LED headlights go for that budget range if so inclined.