Price is going to vary depending on the setup you want. Are you going with leafs or coils? Axle options are numerous but you need to figure out what size tires you want to run to help determine the gearing you need to be able to handle them. For the front a lot of people run a Wagoneer D44. Also are you doing the fabbing/welding yourself or is a shop doing it for you? That will easily double the cost if someone else is doing it.
BTW there is an Axle Section further down the forum where you could find plenty of info on SASing. You could also try using the search for "SAS." You'll find lots of information.