RE: .257 weatherby
I hear you on the premium bullets, nowadays just about anything loaded with a good bullet will cost you.
Remington chambers the .257 in a rifle now too, was surprised to see that.
It's a smoker for sure. Recently read an article on it being a great all around....kinda likened it to the .270, saying for the guy who hunts deer and may occasionally hunt elk, it would be a great choice.
Sounds like your mind is made up, and I see no reason to talk you out of it.
Speaking of wby vanguard, they chamber the .270wsm, that's probably a round you can most liken it to, though I suspect you've already considered all rounds...