In searching to get my "ducks" in order for aeration . I have been seeing these used Gast pumps from "hospital use" Other than rebuilding the vane section if the pump motor runs they should function OK. Electric motors can have a long life.
$200>300 sounds like good deals. The difference between vacuum and compression is just which port you use is that correct ?
Any comments pro or con
http://www.ebay.com/bhp/gast-1023

1023 may be overkill for my 1/4 acre wet spot - see link