Pete,
You can make a vacuum pump from on an compressor from a cars air conditioner and an electric motor that delivers around 500 revs per minute. A couple of pulleys and a belt can get that for you.
Trust me you will use it a lot more than once.
I had a friend who wanted to laminate some timber to make a gun stock. I'm not into guns at all but offered him some advice. I told him to work out the area of the wood and the pressure he could get under vacuum (around 14 psi) and just get bricks and stack them on top of his wood. That way he would get good pressure without a vacuum. On the way home I did some mental calculations and worked out the stack of bricks would need to be nearly 28feet high (8.5m) just to get the pressure he could get with a simple vacuum.

As a side note when vacuuming my F85SR floats I worked out I would need 53 tons of weight evenly distributed to apply the same amount of pressure as a simple vacuum pump. I am now working with 3 different vacuum pumps depending on the job I'm working on with a Milking machine in the wings to turn into a vacuum pump should I get the time. Even with the simple process of glueing two bits of ply together. Do it under a vacuum and you won't be able to see what is your glue joint and what is the production ply glue joint.

Think about it a little and see how it falls.

Regards,
Phill