Found on http://www.tooliday.com/ today for $79.99. I do not have one so I cannot speak to how well it works, but I know CMS dust is a problem for a lot of people.
For all of you looking for a solution to their CMS dust problems, here is a sale for the Fastcap Saw hood. It is $110, reduced from $180. I have never tried it, so this is not an endorsement.
http://wood.tooliday.com/