Its been a while since i did the four link but here is a rough list of parts and prices.
3/4 rods ends $320
Coil springs $150 These are
www.Rockkrawler.com springs they are their 8" front springs for the new body style Grand Cherroke they have a #220 pound spring rate and were about 22" long when i got them but i have cut them down a few coils to sit even with my front lift.
1.5" x .250 wall DOM tubing 20 foot stick $160
3/4" Tubing inserts for rod ends $96
This is not every single thing you need I have not included the steel for the mounting tabs and brakets, coil spring pockets, shocks, limiting straps,or misalienment bushing for the rod ends These things add up but you can get a good idea from what i listed what it will cost you to do the same thing. I love the four link I have it limited so i really dont have that much more flex than you could get with leaf springs but wheel hop is almost gone none from the rear now I need to do the same thing to the front so it wont have any spring wrap too. By the way the cheapest place i have found to buy the Chromolly rod ends tubing inserts and stuff is
www.poisonspydercustoms.com wish i would have looked around be for i bought locally.