A question I can finally answer with some know how.
We don't buy bee vacs. We make them.
Okay we buy the parts but otherwise we make them.
I was given information on how to build one in my moving bees
topic. The actual link is http://www.beesource.com/plans/beevac/index.htm
which I believe is also can be found through the Hive Plans, Construction tips area. There was also a a way to build one similar to what I did which was to use two 5 gallon buckets. I can't quite remember where that link is.
I hope this helps.