I agree with Kevin, you don't need an autoclave for wet laminates. If you want to get fancy with these try resin infusion.

Suitable bagging materials for pre-preg work should be available from who-ever you buy the pre-preg off. Typically the bagging film is green and quite crisp. In my experiance Aerospace autoclaves operate at about 7 atmospheres, but this will be unnecessary for your projects. Aerospace 'claves are also pressurised with inert gases to minimise the chance of them turning into bombs, however this might be a bit complicated for a home build.