You likely have blown shocks and your springs have seen better days. Our cars work on a shock/strut and spring setup, which is VERY easy to replace yourself. If you want to go with performance stuff, do a search for springs or shocks and you'll come up with a heck-of-a-lot of answers. If you want something like OEM, you can re-use your springs and just get KYB GR2s,
http://www.tirerack.com has them for relatively cheap. A mechanic will likely charge you about $225 to replace all the shocks, it's worth it to do it yourself as far as I'm concerned. Also, alot of bushing sare probably worn out, but start with shocks. Then we can start fixing the rest of the suspension components that are no doubt shot to heck.