We live in interesting times. Some ancient (supposedly Chinese) suggested that might be a good thing. Or maybe he thought it a curse....
Don't like the term "oddball cartridge". But it can refer to almost any cartridge (or even bore diameters) having minimal popularity, generally causing owners to develop ammo anxieties. Results: owners wisely accumulate lifetime supplies of ammo/components and retail operations might have very old inventory they'd like to sell. When a new whiz-bang cartridge having no real advantage over existing rounds appears there might be a very short-lived glut of ammo for that chambering. Think 6.8 Western, not trying to pick on it.
Enter the plandemic. Flexibility becomes king. People are using small rifle primers in pistol cartridges, poring over burn rate charts to see if XYZ powder can work in ABC cartridge.
A cogent argument can be made for purchasing a sizeable cache of ammo/components for some forgotten old/unpopular new cartridge when it runs into you. Purchasing the firearm so chambered afterward is likely easier.
Sorry for making this clear as mud, but yeah, buy a .204.
