.22LR as a protection round....
I would advise against using a .22LR caliber as a defense load. I looked into it about 8 years ago & decided not to buy a compact .22LR mouse gun.
Research by Marshal & Sanow(both sworn LE officers who studied handgun calibers in documented shootings) showed that the .22LR round had a 40% chance of a one-shot stop.
Many 9x19(9mm Luger) & .45acp rounds(230gr FMJ) had around a 65% chance.
A .38spl +P is the lowest I'd go for general protection. Some .380acp rounds may work, but I don't care for the semi auto brands out there. Feeding-cycle and jams are common.
$ may be a problem but don't risk your safety over it.