These threads are always fun.
You will get a lot of good advice and a tiny bit of bad. I personally would get a nice .22 either auto or revolver and enjoy shooting it a lot. I noticed CDNN has the Walther .22 target model for under $300.
Once you get proficient with the .22, you can get something more powerful. In the mean time, the .22 will do for protection tho obviously not the best choice.
What do you think of the Ruger Mk III for target practice?
A .22 is way underrated for defense, it may not have immediate stopping power but it will stop em. (eventually)
Cheap ammo, easy to find and fun to shoot.
TT