Ive been eyeing up and fighting off the urge for one of the "pistol" versions of late. I have one of the rifle versions, and while that was a bit of a cluster, once it was straightened out, its been a lot of fun.
The prices have definitely shot up, and around here, they are going for $500-$550 or so. $399 is a great price.
If you buy used, you need to know what you're looking at. They had a recall on them for a spell, and the first gun I bought, which was used, was one of those guns, and it was a royal PITA. Apparently, they had some QC issues and the bolts weren't right. Mine would rarely cycle more than a round or two, and when it decided it would, it would often fire in bursts.
S&W finally made it right after three trips back to them, and replaced it with a new gun the last time back. The new gun has been fine, and a lot of fun to shoot I put a small $100 red dot on it, and its been a favorite of pretty much everyone when we bring it along.