most coilovers have the aftermarket springs with them...if you don't, I wouldn't purchase the coilovers. Now that I think of it, is there a coilover kit that doesn't come with springs?
Eibach sportline gives a nice healthy drop, about 1 to 1.5 inches
Tein sells just a set of springs that drop the same.
Don't go for anything crazier than that. 2.25 sucks... I had mine that low. It was cool, but fuck if I didn't hit everything on the road.

neuspeed sells a set for us, but its a little extreme.
stick with the brands that have names, as opposed to the Ebay special.