After 10 years, I'm kinda' surprised that there isn't some type of XF 'swag' merchandise out there.
Alternative idea.... a pricing scheme like some auto insurance companies where you get a discount based on years of service. For every year you're an XF customer you get an additional X% discount on your renewals & licenses.
When I was on the support staff on ZetaBoards (before the Tapatalk nightmare happened), we convinced the owner to get us all hoodies and that was a good year. ^_^
Hoodies are definitely the best swag, in my opinion.