Hi Robin!!! I'm near cincy Ohio!
My daughter is all the time lookin at the gun case in WalMart! They usually have some decently priced 20 gauges in there and even a model with 3 choke tubes. The 20 ga. will narrow the choice in ammo however, but the set of three choke tubes will give you more range in what you can hunt. You would be able to hunt deer and turkey with the same barrel.
A 12 ga opens lots of doors for ammo, though sporting ammo may not be too much different between a 12 and 20.
Would you say recoil is an issue? If it is a big concern, you could even look into a .410! Only problem with a .410 is ammo being expensive.
Whichever way you go, if you get something with a field barrel, be sure of the choke, it may be fixed meaning you cant do anything to change it. If at all possible with the field barrels, see if you can find the "Accu-Set" I think its called which give you the three diffent choke tube. That would provide the most versatility with a single barrel.
Theres lots more info, and if you dont see what youre lookin for, ask anyone here or try a search!
Welcome to Mossberg OWners!