SirKit's Mom had a old Royal electric typewriter, and we had a devil of a time finding a new ribbon for it! When we did find someone who sold them, we bought several for her. She didn't like the newer, IBM Selectric that she used where she worked, so the Royal was just right for her.
Yeah, I think the older electrics that take kind of unique ribbons can be tricky to find replacement ribbons for. Luckily it's still really easy to find ribbons for old manuals that use standard spools. There are even a few companies still *making* typewriters that take 'em, believe it or not. Guess it's because there are still places where electricity isn't readily available.
I've heard you can also reink the ribbons pretty easily with something like stamp pad ink. Too messy an undertaking for me, but I guess it's good to know.