Record cleaning machine vacuum

I am in the process of building a record cleaning machine and trying to decide what route to go with the vacuum pump. I have looked at several sites and a lot of DIY units use a shop vac. I have been trying to to find a smaller unit like what is used in the VPI machines in order to keep the finished box small. Does anyone have any suggestions on where to look for one? I don't want to pay a lot for one as a 1 gal shop vac at Wal-Mart costs $20.
i am using the small shop vac, modified crevice tool and old turntable plinth/platter as my rcm. i have less than 50 dollars invested and other than being a little loud, works great. plenty of vacuum for the job
I have fabricated a DIY RCM based on a Monks/Loricraft design which uses a Sears 2 gallon 1.5 peak HP shop vac. It sells for about $25. As with any small shop vac, the thing is ridiculously loud in use. The irony would be too bitter to incur hearing damage due to judicious record cleaning using this thing so always wear earplugs or muffs. The saving grace is that the entire contraption cost under $50.

Don't know what type of vacuum unit is in a VPI. A 16.5 is pretty loud in use also but still nowhere near as bad as a shop vac.
Readers : A Bissell "Green Machine" (model # 1653, 1653-1, 2 or 3) are perfect solution for self contained record cleaning machines . Just plug the solution tube and place two "Disc Doctor" felt strips on the mouth of the cleaning head. The units are completely self contained even with a removable brush good for a gentel scrub and a built-in collection tank . They can be had new or used and are a lot less hassel than a DIY costing about $60-70 new , $25-45 used. The new units don't have the same look as the 1653's and may have a slightly weaker motor but are acceptable if the 1653's aren't available. An inexpensive wooden Ikea lazy Susan w/a soft plastic cover completes the project.
Sorry : The exact name is the Bissell "Little" Green Machine , they apparently have other Green Machines that cost much more.