If your brother doesn't mind a little drive then Prescott offers a large number of really great gun shops, all within a small area.
J&G often comes up when people talk about gun stores in Arizona but if you're going to drive to Prescott to look for guns then I would suggest Prescott Valley Guns over J&G. I lived in Prescott for about a decade and while I bought probably a dozen guns at J&G over the years I lived there I probably bought over forty guns from Prescott Valley Guns during that time.
Besides Prescott Valley Guns there is also High Noon Shooting Parlor, High Country Guns & Knives, The American Gun Shop and Bill's Trading Post. All of these gun shops are staffed by older guys who seem more interested in talking guns than selling them, unlike J&G where most of the clerks there are first and foremost salesman.
I would suggest that your brother take a day and drive to Prescott, I'm sure he'll find a handgun at one of the shops up there that will fit his needs.