28 Ga guns are not all that hard to find. There are just not that many used ones around. If you know guys who shoot skeet, that may be a good stating point. Short of that, a new gun may the way to go. Remington 1100 sport in 28 Ga are common, as are Browning Citoris, and their BPS. I believe that Remington 870's are chambered in 28. Your probably looking at $1100 plus for a new gun. I will say that of the shotguns I own, and the shooting that I do, the 28 is the sweetest gauge of them all, in my opinion. I have also heard the same sentiment from many others.