Finding a used 3rd with right gear ratio will be the cheapest way to go.

When I change mine it costed me about $300, including adding in a LSD. Since I have been saving about 3L or $3 for each 100km, I figure my breakeven point is only 10000km, easily attainable in less than 6 months.

So ya, it's worth it because u get all the benefits back, thus slow down excessive drivetrain wear.

91-22re(408xxxkm & counting with a rebuilt long block)- Flatbed/Camper
/33x10.5BFG-AT/Open 4:88/1.5"BJS/
+2"Shackles/Add-a-Leaf/AirLift/Dual-Batteries