I just ordered 1000 rounds of Aguila 55gr .223 from Cope's for $353 (shipping included) This stuff is good, I tried a box to test for cycling and cleanliness and its good stuff, worked fine in my two ARs. Brass case for reloaders.
http://www.copesdistributing.net/product_info.php?cPath=45&products_id=2101
http://www.copesdistributing.net/product_info.php?cPath=45&products_id=2101