A 308 M1 is kinda rare. It's NOT easier to find or cheaper. I've seen to few examples used to say it has an advantage over an '06. In theory, it should have, but
An original is extremely rare. My State Association had three unaltered Air Force National Match M1's in 308. These were sent to Scott Duffy for sale on his auction sight. One was in exceptional condition with a 6 million receiver. None of the rifles ever made to to the auction page. Duffy had buds who wanted these so bad, that he was able to sell them them without listing them. The average sale price for the three was $3,000 each.
The State Association was able to sell two of the rebarreled Air Force NM M1's to Association members for about half of the Duffy price. These were rebarreled with Douglas barrels once the original GI barrel was shot out. Back then, no one knew about these things. They were just rifles to shoot, and keep shooting, for State Association members.