About 2 years ago Cabela's had a sale on Remington 147grn RN FMJ brass 9mm. I was buying stacks of Gift cards at a discount and Remington had a rebate.

I stacked deep 1000s of rounds of 9mm at something like $0.05/ea end price. So it's possible to get factory new center-fire brass ammo for less than 22lr if you get creative.

For aluminum I've never had an issue. I've even reloaded once fired aluminum cases for bunny fart loads I knew I wouldn't be able to recover. Don't recommend it, but it can be done.