I never had a need for a jointer fence. The closest I've come is building some donkey ears for my shooting board. But even then, it has only been because I was mitering lots of end grain and needed precise and consistent angles.

But if I ever did need a fence on a jointer plane, or something like that, I'd probably just clamp a board to the side. Maybe cut a rabbet into the fence or attach a secondary piece so that I could get the iron all of the way to the edge. I don't think it would be something I'd use often enough to justify the space, let alone cost, of buying a purpose made tool. Never mind the time lost buying one.

But, you know, everyone's different. I'm kind of a minimalist when it comes to buying tools. And I enjoy the process more than the product. So figuring out a way to make what I have work has an appeal to me that buying a rarely used tool doesn't.