Depending on what caliber your bolt gun is you may want an assault rifle in that caliber, because that's one less caliber you have to buy/have on hand. You can get a solid AK for about $400 now, and a good solid AR for $600. The ammo for both will run you $220/1000 roughly right now, and either will suit your needs. They are completely different animals, so shoot before you buy. Be nice to Chris and maybe he'll bring you over to shoot sometime.
You seem like a decent guy, so I'll be happy to help you buy/build a rifle that will fit your needs and get you pointed in the right direction for some training. I have owned thompson, m1 carbine, garands, and mini-30 but none of those are going to be competitive with an AR/AK for the price.