Hey, i'm thinking about lowering my car by adding a lowering spring for about 100 bucks in a local body shop, but i also find lots of springs for like 50 bucks including shipping in ebay, which one should i go for????

 

you get what ya pay for with ebay. just save you $$ and then get some full coilovers.

 

I would not suggest getting $50 springs.
Go with the following brands, others may agree or not: Tokico, Eibach, Tein.