It makes no sense at this point to buy new fluorescent tubes outside if you have one obviously bad bulb with life in a full bank and want to keep them going and matched till they are all close to done or done. LED has a better light spectrum (choose your temp pref), higher efficiency, are safe (no high voltage circuit, or problematic ballast). You can replace with LEDs designed to work with the ballast, making it trivial to replace, but it is better to do a little rewire work and remove the ballasts since they can go bad, drop efficiency a bit, and can make noise (though less so at low LED loads).
Additionally, there is another effect if one is responsible. The stuff in fluorescent light tubes is toxic and they should not be broken or mixed in the trash. So you should find places to deal with them responsibly. As the volume went down this became a special ask and less and less places are taking them and might also charge a lot to responsibly dispose of them for you. So the junk gets more and more expensive to deal with. Old ballasts can be put in metal recycling with no issues.
Really, none of us should keep using fluorescent tubes or compact fluorescent lights. There is no reason for them any more. The light is much worse, they are less efficient, they are problematic, and they are toxic. I am not a fan of big government and excessive regulations, but I can understand why states are starting to ban them. It makes no sense to keep them and you do not want them in the waste stream.