Looks like Grizzly put their entry-level air cleaner on sale today. Google seems to indicate this usually goes for $165 pre-shipping. Down to $110 today shipping is $19. Just bought one for my one-bay shop, and it looks like a great little unit. Might even be cheaper than building your own with a Squirrel-Cage fan, depending on where you can get your blower.
Thanks, just picked one up!