It would help if we knew what brand of coilovers you plan on purchasing. The best advice I could give is don't just go installing parts on your car because you feel like your getting a deal here. There's one thing I've learned in my tuning experience and that's, "you get what you pay for".

We could be talking about $50 ebay special coilovers here. Chances are that these coilovers have horrible ride quality, that's why the seller wants to get rid of them.