Any camper supply store will hae what you need.
Campers World is one that comes to mind, Although I personally will never shop there for reasons I will not get into....
You may or, in the case of the one in Center Conway NH, May Not get one.
I got mine at a mom and pop propane place where they repaired propane things as well as sold propane. It only cost a few dollars more than Amazon! Also found real Butyl tape, something I had asked all over town for and couldn't find!