4 link setups for rock crawlers are entirely different than for a high hp street/drag vehicle. I've built an offroad 4 link before but wouldn't dream of tackling a setup for my truck. That said $2500 out the door would be a good price for a jeep. For offroad they are more interested in flex, not keeping the axle perfectly situated. Also they are more interested in designing the geometry of the system to avoid squat or anti-squat (lifting the rear) under acceleration. This is different than designing a system to effectively transfer weight to the rear and plant the tires.
Do a google search for pics of street car 4 links and compare that to what you've seen them do on offroad trucks.
Here is a link to some pics of Jack's setup
Click Here
Attached pictures are one that I built for my jeep. Notice how adjustable Jack's mounting points are. You need all of that adjustability. The only adjustments I can make on the jeep is the length of the control arms to give a little more or a little less squat.