All .375 H&H is brass cased, typically Federal blue box will be the cheapest, usually around $50-75 for 20 rounds, many loads go up over $100 per 20 but there's little reason to pay that. You're smart to look to handloading, handloading is a must for cartridges of respectable size, and you'll appreciate it in the .375 for the versatility it allows you. I've only ever bought 20 rounds, one box, of the Fed blue I mention for my .375. All other rounds have been handloaded, only way to "roll". I'd just handload from the get go.