Regarding Don Barton's inquiry for vacuum units, check out this website:
    http://www.pianoproservice.com/BT002.shtml?mode=preview 

The current price is $270 for a ready-to-go unit.  They also have a
"short kit" of parts, with plans to build your own, for less than $125,
according to their website.

I haven't bought any of their products, but I did save the link for
future reference.

Wade Newton
Fort Worth, TX