Cool finds! I'll bet you didn't pay $5.36 for that box!
About ammo prices:
I watch a lot of C&rsenal programs that include unit pricing on early military contracts. In the 1899 contract with Italy for 5K C96 Mauser pistols, these handguns, complete with shoulder stocks and cleaning rods cost 67.50 Reichmarks each. The same contract included 1.5M rounds ammo priced at 61 Reichmarks per 1K. Using those numbers, this expensive stocked pistol sold for roughly the same price as 1100 rounds of military-grade ammo. That seems like fairly pricy ammo to me, probably higher than today's pricing.
With white box 9x19 retailing for something like .30/round at Cabela's right now, 1100 rounds works out to $332 in contemporary money. Bulk military contract pricing would be even lower.