Available at Parts Geek, Rock Auto etc. The cover is not compatible however as far as I can tell the dyaphram is.

Very helpful! Pointed right where my problem was. Regarding replacement dyaphram only, the VW 2.5 peze i5 has a similar vent system and the dyaphram looks identical. I was able to pick one up for around $15. The package included the dyaphram and snap on single use cover for the valve housing.