you'd need an M10x1.5 helicoil kit. you would drill oversized with a 13/32 bit, tap it with an M10 STI tap, and thread in the helicoil.
since you stripped not one, but TWO of these during your DIY, i recommend you NOT attempt this yourself, as you really only get one shot with these.
and yes, your mechanic may charge $50 an hour, but do do this yourself, you'd need to spend about $60 - $80 in tools & equipment anyway.
EDIT: BTW, this will take your guy 2-3 hrs