Ebay would be a good source. I'd get the boxer primed stuff 'cause reloading the Berdan cartridges can be a pain. There is a wealth of milsup ammo available. You'd have to be kinda selective about corrosive primers (no biggy, just clean your rifle well after use) and Berdan primers.
I just ordered 100 Remington cases from Midsouth and called it happy.
Reforming the 30-06 would work but be time comsuming considering how cheap and readidly available the proper brass is.