IMO the 250 is a dieing cartridge but that's no reason not to get one if you want one. Bullets will always be available as will powder and primers. Dies will forever be available - just look at the odd ball stuff RCBS is still making. The only question is brass. As others have said you can make it out of 22/250 or, if I were you, I would just order a couple hundred pieces when you find them and you will be set for life.
I have a 350 Rem Mag that is even worse to find brass for, when I saw some brass for sale I bought 300 pieces. Now I'm set for life.
