lets just say you get what you pay for.....
10 bucks for coil overs????.........A cheap basic set of coilovers costs like 600 bucks...Full coilover kit..
Your best bet is that. Or just get good springs ( about 100 bucks, eibach, h&R ) and good struts......
Dont get that eBay garbage you'll regret it.
My friend bought some eBay springs and his car bounces all over the place.