Bigger than CMP running out of Garands is CMP running out of HXP ammo. What good is a rifle if the ammo is tough and/or expensive (unless you reload) to find?
Once that's gone, there is no reasonable source of cheaper surplus or new ammo to shoot. How does PPU run per round?
PPU is good stuff and reloadable. Federal makes Garand specific ammo and I think someone else does too. There's also plenty of Pakistani POF surplus, Korean KA & PS surplus, Danish AMA surplus, Taiwan too I believe. Reloading is the best way since you can make far more accurate ammo for cheap and its really simple.