I've carried Glocks (9mm, 40 & 45) most of my career and they are in your price range. Most women will prefer the lesser recoil of a 9mm.

I agree with taking your wife to a gun store and letting her handle different pistols to see what she feels comfortable with. She may actually prefer a small revolver instead of a semi-auto. If your primary use for the weapon is your wife's self-defense while you're gone, it really needs to be something she is comfortable with and doesn't mind shooting. Good luck and let us know what you decide.