I'm guessing you want to keep costs down (who doesn't), so rather than buying one off ebay, may i recommend you simply modify a "henry" hoover to do the job.
Fortunately i have a bit of experience with the shot blasting industry (did it for 5 years) and the industrial extractors we used on nearly all of the small to medium sized machinery were little more than over-sized henrys, admittedly they used 3 henry motors rather than 1, but i don't think you will be needing the 7500 l/min that we needed.
I would suggest that the standard henry base will not be big enough, however if you can get your hands on a round 5 gallon drum (I believe a Morris lubricants 5 gal drum is about the right size

) they should be a pretty good match for diameter to get a decent seal. And with any luck it should look something like this...
http://static4.shop033.com/resources...F/15677167.jpg
Also keeping it simple with henry components should keep any repair costs to a minimum, after all how many of us on here has one somewhere?
And if its good enough to be used on asbestos removal, i'm sure it will do the job for your cabinet.