I used a set of diaphragms I got off Ebay, they are made and shipped from the UK and run about a bone for the set of four. They also were more robust than OEM but the fit was proper and they work quite well.
I dont see a link but I checked out the JBM site and I cant see any information on where these are manufactured, but I'm still pre-coffee, I could have missed it. I think that is a great question for them. Its critical to make sure you don't end up with something made in China or from Chinese (global is a new buzzword used to avoid actually saying China) materials.
Global materials = Chinese materials
US seller = US seller selling Chinese junk
Manufactured in one of the following countries = China
Ships from the USA = Chinese junk that someone already ordered over here and is now trying to liquidate.