You can usually find pretty good deals on legit name brand parts on ebay. But please do yourself a favor, and save up a little longer and buy a quality part. The unbranded cheap stuff on ebay is crap to say the least.
Personally i have had great success with Eibach sport lowering springs. They are not a conventional coilover setup. But this lowering spring coupled with a decent damper will improve overall handeling and performance. Its cheap, very affective and best bang for your buck IMO.