Quality Cartridge catalogs it at $36/20.
It can also be formed from
.303 British and .30-40 Krag (stronger case, but much harder to find). Or, usable, but not ideal - .220 Swift and 6mm Lee-Navy brass can be used for forming (though 6mm Lee-Navy brass is nearly impossible to get).
If you decide to take the forming route - I'll have some .220 Swift and .303 British brass coming up for sale within the next week. My Swift is being rebarreled to .243 Win, so I'm in the process of pulling down all my hand loads, and organizing/cleaning the brass. The .303 British cases are all new, unprimed. The .220 Swift brass ranges from new/unfired, to once-fired, to twice-fired (I have more beyond 3x fired, but it is too brittle for forming to .303 Savage).