In the typewriter space, the closer you get to the people actually manufacturing typewriter ribbon, the cheaper it gets. As a result you can buy ribbon in bulk for about US$2 per spool versus $10-15. In America, I've had excellent experience with Baco and Fine Line: https://boffosocko.com/research/typewriter-collection/#Typewriter%20Ribbon
Mostly on Amazon and similar platforms you'll find resellers selling for top dollar. If you're going to do this, then the better route is to spend the same (or possibly a bit less) and get your ribbon from a local typewriter shop which helps keep them in business for the eventual day you'll need a more serious repair or help. Try a local shop from the list at https://site.xavier.edu/polt/typewriters/tw-repair.html
If they're close, your local shop will also help teach you how to respool ribbon and thread it properly as well as potentially other tips and tricks.
reply to https://old.reddit.com/r/typewriters/comments/1q095fg/just_bought_a_typewriter_any_tips/