I started looking into the Saiga rifles, and for the price, they don't seem too bad. I haven't looked at any reviews yet, but maybe I will today after my exam. Imaginefj has a good idea with his recommended collection.

I did find that Mossberg actually sells a semi auto shotgun, the 930, for a retail of ~$550. Looks like it can be found for around $480, though. If I had my way, I'd have a nice handgun, a shotgun, a 10/22, and a bolt action rifle (at least a .30-06). The handgun would be the least important due to the lack of accurate range.