http://www.natchezss.com has 45acp blazer for $8.29 per box if you buy at least 10 boxes.
That's the cheapest I am aware of at this time. Blazer Brass is under $10 at Walmart. +tax of course.
45acp ammo prices are creaping up and I have been told by a couple of retailers that Winchester is NOT shipping any white boxed 45acp, 9mm or 5.56 to consumer retail centers until after July 15th. I also heard that JUly 1 there is going to be a substantial price increase.
My favorite factory target ammo, Winchester USA45A 185gr fmj (not winclean), is nowhere to be found. I have a single case left and I am treating it like gold.