You can drop a 4x4 for really cheap. Go to www.blazinlow.com and do a search for the torsion bar trick. You can get a considerable drop in the front doing that and it costs nothing, then you just need to get blocks for the back ($30). Hope that helps.
Basically nothing. The torsion bar trick can be done yourself that is if you are handy. It involves taking out a cross member and notching it so the torsion bar keys are in a different position so in turn lowering the front. There is also a way to do it by just flipping the torsion key. Just search blazinlow.com in the metal drop and 4x4 sections and you should be able to find out how to do it. Then in the back its just putting the blocks in.
Dont unwind the torsion bars, reset the key location or flip them, it'll screw the ride up badly, create alot of rebounding and you'll eat upper balls joints. Also rear blocks for lowering on a 4x4 are a no-no, under 4 wheel drive conditions you will eventually snap the center pins off due to the loads differences between the front and rear. Use only drop keys and dearched leafs in the rear. Bravadas and such with there smooth ride suspension are lower by about 2 inches than a standard 4x4, you can use there rear springs.