if its just a pinhole in the boot and hasn't been run dry, I can't understand why you wouldn't just pull the axle off, take it to a driveline shop, pay them the ~$60 they would charge for a rebuild, put the axle back in the car, and have it all done well within a day. I did this and mine is still in PERFECT condition after about 9000 miles.
I agree. The upper boot is technically independent of the CV joint. The $50 Mazda boot kit should be all that's required. Comes with the boot, rings, and grease. Mine went out as well. As long as there's no noise you shouldn't need pay $380 for a replacement assembly (though you get $85 back with core exchange).
For more serious tears, some shops will clean the assembly to ensure it's free from contamination. But it sounds like this won't apply to you. GL.