i think I've got an extra gasket at home from when I got my regulator. It's my only extra one, but if you have trouble finding one for sale somewhere just let me know. I'll let you have mine. I've had my CO2 tank for about a year now and no problems with leaks or anything, so I'm thinking/hoping it should last for a very long while
Mailing it to you would probably be easiest, just say the word!