I have a S&W version that shoots red flares, I picked it up for $10.00 at a gun show a few years ago. Here's a link to a current (8-20-2010) auction of one:
http://www.auctionarms.com/search/di...0346&oh=216543
As far as the legality, mine has a sticker that says it's not considered a firearm under the NFA when used for the purpose intended.