adjustable air shocks for rear 87 ciera

i have a 87 cutlass ciera that im gonna drop in the back, and im lookin for some adjustable air shocks, that i can raise or lower while driving, (for speed bumps and stuff). they dont have to rise really fast, maybe 10-12 secs or so. thanks for any help.

oh, and im tryin to go cheap, so if possible, i dont wanna spend to much more than $200 on them. thanks