If you're looking for barrels, check out Midway. They currently have a .480 Ruger stainless for $175, and will have .454 Casull stainless on sale next month for $179. I haven't shot either (I like my .44 mag) but thought you might want a heads up if you're considering either.
As for accuracy, I can shoot a ragged hole from a rest with the .44 mag at 50 yards, and that opens up to about 6 inches at 100.