I paid $925 for mine freshly rebuilt complete everything down to the kickdown linkage cooler lines the works. If your replacing a standard all the parts needed add up to about $1400. I had to pay another $175 for shipping so keep that in mind. The killer on the C4 is the intermediate housing and shaft at $500, I would probably do it again for the complete conversion only. The other route is buy a C4 and housing kit and your easily at a $1500 then another couple hundred for all the little stuff (linkage, lines shifters and what not).
Maybe you could find a intermediate housing and shaft from a donor truck and then buy a nice aftermarket C4 for around $800 and be set.
BTW those aftermarket intermediate housing kits are not exactly the same as an original they are a different lenght so you can use your original 3 speed driveshafts. But I had no problems using mine with a 2.5 inch lift.