For your purposes and budget, don't get one gun for home defense and for target shooting. Get a target gun for the time being, which can be used for pure self defense though it won't be ideal. You can pick up a good used self defense gun, should you want one, for $150 or a new one for $300 or less.
Also, is this just for you or will your wife be routinely shooting it? I am thinking that you can get a lot within your budget if you look at used Citoris.