$475 seems to be about the average going price now days. Some more, some a bit less.
With the different gas settings, you can adjust it to shoot different ammo. One of mine would shoot the light loads right off, as well as slugs, with no problem.
I like the fact that they do not kick the crap out of you, like other 12ga shotguns. The Kalashnikov action absorbs a LOT of the felt recoil. And I have heard that they are (arguably) as fast to shoot as a Benelli. I know I can dump a 10 round mag in "probably" less than 3 seconds. Have not "officially" timed it yet, but plan on doing so later this month.
LOTS of aftermarket stuff for them. You are limited only by your wallet.