It sounds as though you have a specific rifle in mind, rather than the cartridge. Certainly the cartridge does not have a great deal to recommend it, but the rifle might. Would you care to enlighten us in that regard?

I once had two 400/360's in my store, one a William Evens box lock and the other an Alexander Henry bar action side lock. The each went for under $2000, but that was long ago, and I would gladly have either one of them back.

If you are interested in the cartridge, rather than the rifle, the 400/350 has much more to recommend itself, and you can make brass relatively cheaply from 9.3X74R cases.