the ebay coilovers arent as bad as everybody says. the only way they will bounce alot is if you have REALLY sh*tty shocks, or your car is too low. the springs wont be as high quality as eibach, tein, or any other name brand.

IMO, youre better off buying the coilovers AND new name brand springs. cheap adjustability + good spring rates is what your looking for. and dont go cheapo on shocks. while ohlins and motons might be out of the budget, you dont want cheap shocks. KONI FTW.

as far as autocrossing goes, autox your car in stock form first, and go from there. theres ALWAYS plenty of helpful people at those events.