Joel;
The reason they cost a lot is due to the fact that they have to pump out 3-5 GPM against 16" of vacuum.
Most pumps will NOT handle that vac level....
Or that much trash....
The
ProChem diaphragm pump has just recently jumped in price several hundred dollars.
We tried some less expensive pump-outs, but they have to be serviced fairly often.
Larry Cobb