In 12ga the turkey loads can be good because they won't penetrate into a target too far. Good if you have thin walls that you're worried about going through, or if your really, really don't want to kill someone you shoot at. One strategy if you do need penetration or lots of damage is to alternate shot with slug. Shot gives you the pattern for a little more sure of a first round, and once on target one can follow up with a slug if need be.
You don't need expensive ammo, but reliability is one thing that comes with cost. Don't go too cheap. Someone suggested #4 shot, and this might be the best compromise of all performance factors. You can probably get that cheap enough.
A good 1911 is always nice to have on a bedside table as well. I've got a 14+1 Para that is too big to carry comfortably, but goes nice with a tac-light and has all I need to welcome guests in the night.