Check the reloading board. Plenty of discussion & math on this & most other gun forum reloading boards.

As for saving brass, just do it. As somebody else said... "It doesn't eat anything, it doesn't go bad & it ain't getting cheaper."

At 200 rounds a week you're already there. You can get set up for $300-ish.

FWIW .357 brass is always gold whether you reload or not. During The Great Ammo Drought of '09 it was the one caliber that got snapped up immediately on the WTS boards. Even Starline was backordered.