help with some suspension purchasing?

hey guys sorry for the rook post but here goes:

just got into mtn biking about 3 months ago, my friend sold me a trek singletrack with rockshox (that are busted). i dont wanna go and buy a new bike yet as i dont have a lot of money and i wanna get better first also, now i wanna remove the fork and get a new fork for myself that isnt too expensive but has about 80-100mm travel. ive been looking at some rockshox like the psylo and pilot but have read some pretty bad reviews on them, anyone got any suggestions for about or under 120-150 bux? also does anyone use those rockshox seat posts that provide a little bit of "rear" suspension? does that help at all on a hardtail?

thanks in advance.