Epson usually restricts their parts from direct sale to end-users. Also authorized resellers frequently are prohibited from shipping out of their jurisdiction. For example I tried ordering some stuff from Compass Micro to do some maintenance on our 11880's, and CM would not ship to a Canadian address at that time. It's the same even with basic supplies like Epson OEM ink cartridges; all the authorized USA resellers I've tried will not ship to Canada. So I'd say talk to an Epson dealer and get them to order the parts for you. That's what I do here in Calgary.
Also, I personally would stay clear of the Chinese-made knockoff dampers that you can get through Ebay and such. I've tried various knock-offs before, and they fail in all kinds of ways -- damper valve stuck closed so no ink flows, valve sticky so nozzle "clogs" happen much more frequently, valve stuck open so ink just pours out of the head when the system pressures up, etc. I only use Epson OEM parts now. True, they are more expensive, but so far they have always worked, and the knock-offs for me have always been trouble. Usually I can see the differences in the manufacturing when I compare the parts side-by-side.
Ink and paper are more expensive over time than a few bucks for good printer parts, so now I don't try to economize on the maintenance side of things. Operationally I'm miles ahead by minimizing consumable waste. Part of that is not risking a compromise to the ink delivery system of the printer by installing bogus parts.