It does not eat up barrels fast at all. About the same as a 223, and significantly longer than a 22-250. It's not difficult to find anymore, except maybe if you're looking for factory ammo. Brass and bullets are easy to come by, and there are about 8 or 9 different bullets out there, by all the major manufacturers.
The 204 is essentially the 22-250 - same or slightly better trajectory, and slightly less drift, with less noise, heat and recoil.
I just got my Remington back from a warantee repair, and shot a 5/8" 5-shot group with it. And that was just while I was sighting it in, I wasn't giving it cool-down time between shots, or really taking my time with it at all.