There is a company called SDS that has exactly what you're looking for and at that price. They market their stuff for watercooled cars but I don't see why it wouldn't work on the airsuckers. I think it stands for Simple Direct System or something to that effect and they do have a website.

Email my buddy John, he knows the site and info as he's doing it to his '75 1303 H2OSB@superbeetlesonly.com