usually you can get away with just new bearings if its still changing gears fine, i rebearinged my r30 box for under $250. not the hardest thing to pull a box apart and put it back together, did the first one with my dad and the second one by myself. even then when its apart syncros are pretty easy to replace if you can get some new ones...dont know if you are supposed to do anything else when you replace syncros though

ask revhead, he works for hollinger and builds gearboxes for a living