Everyone I know that shoots 300BO reloads. Considering the amount of .223 left over from a qual day, there's plenty of brass to cut down and resize. Only thing you have to actually buy are the primer/projectile/powder. The reloading allowed him to really tweak what his gun likes both su and super sonic.
In my opinion If you have to reload to offset cost of ammo or "tweak" a round then that's another reason not to own 300blk, if im gonna reload i'll reload 308, and i would say most people don't reload, they just want to go to dicks or the local shop for ammo.