I'm looking to start replacing my shocks beginning with the rear. I want some pretty good for rough terrain and good for jumping (not 50 feet or anything!). My funds are severely limited though.

The words "good" and "cheap", when used together comprise an oxymoron. There ain't any such thing. Look at CT Racing's page for the story on rebuilding your rear shock for a "good" price but not a "cheap" price. The other alternative to a rebuild would be $700 to $800 for a new one

the cheapest one i have seen are by works. but if you want good ones its gonna cost ya