I don't like Wolf... but I have shot plenty of steel cased ammo in AR15's without any bad effects on my weapons.
Steel cased ammo isn't my favorite, and specifically Wolf is not my favorite... because it's not very accurate and I have seen just too many blown primers with it. I'll admit, I still shoot it occasionally in some of my Russian guns...
At any rate, I have built some freakin sweet AR15's for family and friends, with all the bells and whistles, and I have yet to see the price get above $3K... maybe he just got ripped off.