if u wanna do springs/shocks i'd go with something like what i have, depending on how low you wanna go..

i have kyb AGX adjustable struts and eibach pro kit springs (1.3-1.5" drop) i am very happy with my setup.. if you wanna go lower i'd suggest the eibach sportlines or H&R sports.. as well as different struts maybe tokicos since konis are out of your price range.. going lower than 1.5" on agxs voids the warranty... if you wanna adjust the ride height, ground control is the only way to go.

if u want a lil more HP and a better sound, you can prolly snag an intake and exhaust for around 500.. the standard is the AEM cold air intake ($175) and good brands of exhausts to go with are Apex'i, Comptech, Greddy, Tanabe and HKS, just to name a few.. it all depends on how you want it to look and how loud you want it.. i have the Apex'i world sport cat back.. its very quiet and looks pretty much like stock (minus the 4" tip :exnbp but i noticed some low/midrange power gains.. i got my exhaust for $280, but it was used.. a whole cat back can cost anywhere from 380 (apex WS brand new) to 6 or 700 (HKS)..

body mods.. you could snag a front and rear lip for around 250 bucks and get your side skirts painted to match.. that might go for around 500 including paint..