I picked up a brand new Mossberg 500 20 gauge with a smoothbore and a cantilever rifled barrel this summer for my wife to use.
I have $315 in everything. And it could realistically be used to hunt anything my wife is ever likely to hunt. She'll just use it for small game and some special regulation area deer hunts.
I haven't shot the slug barrel yet, but I have faith that it'll be a good shooter to 100 yards.
I'd recommend buying a slug/field combo in either Mossberg 500 or Remington 870.
Then go hunting.
-Jake