Gator is a good company, good service, good pricing. Axle rebuilds are typically in the hundred-dollar range (call them for exact details). I've been using them for a couple years now, been extremely happy with their quality and service. I regularly send them axles for inspection/repair/repack.

I suggest scouring junkyards for a spare pair of OE axles; you can usually identify them via the paint marks on the shaft. Send those to them and keep handy as spares.

Other racers also like to use Raxles (http://www.raxles.com/).