If you handload you're probably ok. Remington still lists brass for sale from time to time (midway is out at the moment, but you can find it if you look around). .358 bullets of course are easy to get from < 100 gr all the way up to 250gr...
I do not believe there is any 357 max factory ammo available.
It's not elegant, but you can get by with using 357 mag dies for reloading.
If I were to find one for a good price I'd pick one up.
Nate