I agree with 1oz, go for a combo deal pump gun.
It is out of stock at bud's, but this mossberg combo would do you well. They have them just about anywhere that sells guns. If you can find a used one, then I would get one with the longer barrel and add the shorter barrel later as they are cheaper.
http://www.budsgunshop.com/catalog/p...ducts_id/46907
I don't know whether it will last the rest of your life, but by the time you wear it out you will have gone through so much ammo that the cost of the gun would insignificant.