There is a plastic Scan-Tech "updated" one, and in this case "update" likely does not rhyme with "better" but I imagine it works OK for the money. Essentially the VW valve setup, but comes with hoses and brackets and presumably instructions.

They are not however, the original setup, which was more than just an open/closed valve on a cable. Myself, on old cars, there have been very few that I've ever used anything but full hot or full cold. Here in N.C. anyway. So the plain cheap valve is likely alright.