A front or rear regear is not for an average joe. That are many small steps required that take precision and the right tools. If you are not mechanically inclined and do not obtain the tools for doing such a job DO NOT ATTEMPT. Let the professionals do it. Essentially you're paying for top service and in most cases, a warranty. There are many companies that do so.
East Coast Gear Supply
Trail Gear
Marlin Crawler
and others...