7.62x51 / 308 is very expensive, but I think demand is decreasing because prices are too. I recently saw "milspec" 7.62x51mm NATO FMJ for $8.75 / 20 rounds. This was brass case ammo.

$437.50 / 1000 isn't "cheap" but it isn't that much more than quality brass case 5.56x45mm.

I shoot Wolf 223 all the time, but haven't had the heart to buy any steel case 762NATO. Now that brass case prices are dropping I might be able to get some use out of my Scar-17 or FAL.