223 is definitely cheaper than 308, no doubt. But it could be worse. I just tracked down some of the last 5.7x28mm ss198lf on the market at almost a dollar a round.
Damn Secret Service and their stupid contract decision to carry Five-Sevens are destroying the civilian market for ammo.
But I did just get 200 rounds of 50AE for less than $1.20 a bullet, and that is a phenomenal find, considering that most of it is $36 and up for 20 rounds.