You might want to try calling Heatcon 800-556-1990. They make heat blankets and they make a fairly inexpensive heat forming kit that can also be used to do composite curing.

A shop vac only gives you about 4 to 6" Hg vacuum (2 to 3 PSI). A vacuum generator will give you 28" Hg (about 14 PSI). You can get these at places like Heatcon for about $150. (Their part number is HCS2026-01. You can find them on the web, located in Seattle.

You might try Heatcon's HCS2026-01 vacuum generator. The device is about $150 and works off of your air compressor to generate about 28" of vacuum. Heatcon also sells vacuum bagging materials and composites in small quantities. You can find them on the web.