the one i own is a used Gomco 3001 i bought/won on ebay for $50. it's a medical/dental aspiration pump, oilless, 100% duty cycle and came with regulator and gauge - it pulls 22Hg+ all day long but with the regulator i can dial that down to whatever i need. $10 from a medical supply got me an overflow canister with float valve and filter and a set of suction tubing.
i would stay away from the pumps that require oil.
I agree with Rawlus. I also have a medical aspirator/suction pump that I bought on ebay. Gomco is a quality brand that's been in the medical suction business a long time; however, any medical suction pump is going to be high quality and rarely will you have any problem with them. They are used extensively by hospitals for suctioning body fluids (blood, mucous, etc.) from patients. They are kept santitized by hospital clinical staff and only the tubing and collection canister come in contact with patient fluids so there's no danger of contaminating you or your wine; however, if the thought of this bothers you then you may want to stick with industrial suction pumps. If you get a medical pump and ever have a problem with it, just call your nearest hospital and ask to speak to someone in the Biomedical Engineering Department for advice.
As Rawlus said make sure whatever pump you get is oiless (which all medical suction pumps are) and that it has a vacuum gauge (which all medical suction pumps will have).
Sometimes surplus medical equipment dealers won't sell pumps to individuals as a matter of policy, but most sellers don't stipulate this as there's really nothing harmful about them.