Start hitting gunshows.
Loaded ammo and brass is still readily available in .30 Remington. It was a very popular cartridge for a long time. You can also buy brass I believe from Starline.
Start handloading for it. It's not that expensive to get set up with a very basic loading rig.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.