Should have bought a Jeep
I'd guess 30-40k. Depends on axles used, air lockers, tire size, etc... If you want to run huge tires ala @nukegoat style I doubt any shop would do it for less than 80k.
Most people are better off buying the nicest 80 series they can find; or waiting a few years until 105's become importable.
The cost of just parts under the Lexus is approx $32k in case anyone is keeping track. Probably 25k of that is the SAS componentry.
Axles, wheels, tires, suspension, steering, links, skid plates, bumpers, etc.