The RCD coil-over conversion eliminates the torsion bars, gets you 5.5", and it costs about double what the Superlift costs.
Dixon Bros. Racing also has a coil-over setup with longer control arms and stronger halfshafts and costs even more than RCD, about $4500 IIRC and installation ain't gonna be cheap either. Oh, and you'll need flares or fiberglass fenders to cover the tires too.
The Trailmaster kit is slightly cheaper than Superlift but it is said to be weak and not really worth it for the little bit of money you save. Uses ball joint spacers instead of new knuckles like the Superlift.
If inexpensive is the operative word here, just go with a bodylift.