Most labor shops charge 65bux an hour now and days.
The biggest problem is how hard it is to get the old bolts and nuts off. THe shop that did mine had some real issues up front with mine, I dont remember what they charged me, sorry.
also with 4" you may need new dropped pitman arm, lower TCase and long brake lines, all this would add up as well. I only went with 2" lift and it was mainly to fix the saggy 20 year old springs I had. Im only running 33s and dont plan to run anything bigger, maybe 35s later on but I think I can get away with the 2" lift If I do.