Tim, I get Federal 115 grain FMJ ammo at my local Walmart for just under $17 per 100 rounds. It was about a $1 more but they've reduced the price (I didn't ask why, I just bought some for plinking.)
I have a few rounds of 115 grain FMJ Winchester ammo left in 100 round box. It was both dirtier than the Federal and shot bigger groups. In my gun anyway. Oh, in my AR 9MM carbine, too.