Are there any suitable replacements for the diaphragm? Or are the rotax name brand ones the only ones that should be used?

I found this source and it's significantly cheaper than all the other places that are "Aviation" based.

http://www.capitalcycle.com/Diaphrag...ING_p_290.html

Also perhaps there are other things relating to the 5 year rubber and carb flang that can be sourced else where than Rotax?