There's always an attempt by Garand "collectors" to pretend that there's some sort of shortage. There never actually is. There were 5 million of the darn things made. Some have been scrapped or captured by hostile nations, but the vast majority are still out there. Instead you've got people buying insane number of rifles from the CMP in violation of at least the spirit and probably the letter of the law. This is a concerted effort to prevent the CMP from stocking so they can increase prices on the secondary market.
The issue here is criminal behavior by the CMP and a small number of their customers, not any sort of shortage.
Even with that, the vast majority of grades have at least some receiver type in stock. So let's not get TOO excited.