A rubber stopper and some adapter fittings from Home Depot or Ace hardware could do the same thing much cheaper.
If you have an air compressor or access to one with a 20 gallon or lager tank, Harbor Freight Tools has a vacuum pump
http://www.harborfreight.com/air-vacuum-pump-with-r134a-and-r12-connectors-96677.html for $16 on sale.
If you're really economical, an old refrigerator hermetic unit works great as a vacuum pump - $20- $40 at used appliance stores, or go to the Dump and get one for free. Be sure to have some R12 compatible oil handy to keep it lubed up properly.