If you want to go cheap, as memtioned by others on this board, you can pull your current leafs out and just add one long leaf to each while removing the smallest leaf. Thats what I intend to do with mine and if that does not get me the ride heigth I'm looking for, I'll then try rearching my springs and finally look to the more expensive after market springs as a last resort.
One word of caution, don't go with the cheap import springs that a lot of discount part dealers carry. They claim to give you 1" lift over stock and that they are "Mopar" springs, but in reality they are cheap imported junk.
Remember you will never be happy with the quick fix from air shocks unless you like to hear your teeth rattle.
Also, see my thread here under Suspensions titled "Leaf Springs Tooooo Low" for some additional input by the guys.
Charlie
70 Challenger
69 Camaro RS