I prefer the stainless. I like the idea that I can expose it to Rocky Mountain weather and still look showroom new after years of use. (No scratches, rust pits, etc)
Consider this: The U.S. Army's crack and exclusive sniper squad all shoot stainless barrels. They also prefer the .300 Win Mag!
Oh yeah, the 2nd half of your question . . .
I believe pricehas a direct corellation to the quality of materials and craftmanship, no matter what product you're talking about. Another truth: many companies charge according to what the "market will bear", instead of what it cost them to make it.
All that being said, I don't think you could notice a difference in accuracy if you had the opportunity to shoot any 3 or 4 rifles of varied price in a side by side test. I personally took more big game with my Savage 7mm Mag than either my Ruger MarkII or Sako .338 Mag. Probably if you were seriously going into competitive bench shooting, you'd want to pay for that minute difference. But expect to be beat out by the guy next to you shooting an old Ithica!