This silicone diaphragm is perhaps the last you will ever have to buy.  Silicone will out last any other rubber products out there.  I do not need to tell you Voit lovers what OEM gray diaphragms are like today.  TheSCUBAMuseum.com  has a limited number of 2 stage diaphragms available as well for you Voit Navy divers out there.

Price $20.00 plus shipping.