ummm... it was a while back... but i wouldn't have spent more than 300 or so...
then i went to my friend's shop and we successfully installed them (front and rear) within an hour!
I could feel the difference in driving right away... of course new tires also helped a lot!

regarding buying stuff off ebay... i would be too worried. First of all eBay is very strict when it comes to serving customers and if you get f***ed over by somebody, just tell eBay and you will get your money back. Then if you know exactly what you are buying (let's say you want Eibach springs) search for the auctions of NEW Eiback kits (of course do some research first to see what kits are applicable for your car).

Good luck!

let me know if I can be of any other help

dimaj