From your photo it looks like the thread mangling starts about or a bit less than one full turn of the thread. If you got it in more than one turn you
likely contributed to the mangling. You can mechanically straighten or remove the mangled part of the thread with a narrow tool tip, eg 1/8" straight
blade screwdriver or cautiously dremel down the mangled part and probably salvage or at
least remove the crank. A google on L hand square taper crank arm brought up Niagra Cycle with cranks for $10-20, Amazon will also do as a source.
This will give you a minimum cost to
look at: 1)chase thread if you can find a shop with a chaser; 2) try my approach (I did this to salvage a DA hub cassette retainer thread, it was Ti,
but a bit of scraping and dremel work got rid of the bunged threads and the cassette retainer has worked well since (about 2 Kmi so far));
or 3) buy a new crank. If there is a coop in town that would be another source. The crank puller would probably serve as a thread chaser
IF you could get it started right, but I doubt that will work without some thread scrape/grind before hand. FWIW the puller will not work if you put the crank fixing
bolt washer in place, the working end of the puller has to push directly on the axle hole. Putting the washer in and torquing the remover will strip out what threads are left in the crank.