Hi Bart

I have heard of folks making their air compressor into a vacuum pump but haven't done it myself.  I would be a bit concerned about the continuous running of the compressor since you can't stop until the resin has solidified sufficiently to not suck in air and expand.  

Another idea is to use an old refrigerator compressor as a vacuum pump.  A friend of mine did that and it apparently worked well.  One thing I forgot to say is that it is very important to have the pump placed far away from the part and preferably in another room.  The reason is you need to listen to the bag for leaks.

Another techniuque that is great for large projects is to hook up a "Y" valve that you can put on your shop vac.  This gets out the large amounts of air volume present in a large bag. Then you shut the valve and switch to the high pressure vane pump.

Another "Quick and dirty" is to buy long packaging tubes in polyetheylene.  Rather than seal a mold, just stick the whole thing in there and seal the ends.  Works great as long as you don't tear the bag in handling.

Bagging successfully is practically a book in itself but practice makes perfect!  And planning ahead is a MUST!

Dan