In another thread I mentioned how I have a 1100 gathering dust and thinking about cutting one of the barrels I have for it down to 18.5" for HD.
1100's tend to be a touch heavy (soft shooting!) but dead reliable. O-ring will go thousands of rounds and the gas rings forever. I've seen clean, used ones go for as low as $400. That's a bargain for a great semi-auto shotgun.