Just got Jeff's Outfitters catalog and on pg. 32 there are 5 round leather cartridge wallets for $19.95. Available calibers are: .375, .450/400, .470, .500, .577 and .500/.465. These are the ones with a flap, fastener, and caliber stamp. The price seems quite reasonable.
I would get a couple, but all I have now is farmer caliber 9,3x62 and CZ550 clunker so I carry my ammo in camo cloth ones bought at Walmart.