About $1000, depending on your differential, for a 4x4(~$500/axle).
A ring, pinion, and installation kit can run $150-300, installation was running about $250/axle when I had mine done.
Differentials vary; my '89 F250 had the Ford/Stirling rear axle. Nice axle. I was able to swap from 3.55 to 4.11 without changing the differential itself. The solid axle I got for the front already had 4.11's in it.
Others may require a different sized differential to hold a larger ring gear. For instance, the Dana 44 in my old Jeep CJ5, required a different differential for gears lower than 3.73; when swapping to 4.11, 4.27, 4.88, it required a new diff.
If you need a new diff, they can run $150-1000 depending on if it is an open diff, limited slip, posi, locker, air locker...
For a shop to do, it takes a couple hours an axle.
You really have to identify what axle and differential you have. If you keep your diff's, it is not too expensive. If you have to get new diff's, the $$$ pop up.
If, you went to a junk yard for a front or rear end, you could easily pay $1k or more an axle, especially for Dana 60's and Dana 70's.
This does not involve the transfer case at all.
Just what is involved in going to 4:11?
Go to junk yard and get 4:11 rear end and front end? How about transfer case?
Thanks,
Joel