[Lynn Eades]

I guess you take the axle and nut to a machinist who can cut or clean up the thread on a lathe,or use a thread chaser to clean it up. Cheaper than USD $70.00 plus freight, then you want a die as well.
How many do you need? and is it the nut or shaft or both. I bet Colin Jones can make or repair both at home (at price of course)

depending on the extent of the problem,you can clean up the axle thread with a triangle file, you can run the nut on a bit and tap the flats with a hammer. Try inter changing nuts on axles, use anti sieze. etc. etc.