Do a google search and see what the costs are. Also the age/condition of the tire itself is going to be a factor. If the tire is over 6yrs old, or if the side walls are cracking, you would be better off just buying new/new used tires. Check craigslist/Pirate 4x4/Marlin, you can usually find tire/wheel combos for under $500, I don't think you could a set of tires re-treaded for less than that.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed