For the most part the difference between a standard action and a magnum action is the boltface and not much of anything else.The .257 doesn't need a full length magnum action.
The .257 Weatherby doesn't need Weatherby brass, though it is good stuff. Run 7mm Rem mag through a .257 die and you have all the cheap .257 mag brass you want. Certainly cheaper than Nosler 25-06 AI, and without the expense of fireforming 25-06 brass.
I am not exactly enamoured by Weatherby free-bore, but it doesn't seem stop the crummy barrels from delivering hunting level accuracy.
What else ya got? It seems like the .257 Roy is less fuss and bother than the .25-06 AI.