Don't forget Bulkammo.com, luckygunner.com
Like others have said shop around and factor in prices with shipping. I have had good results shooting all of the "popular" stuff, i.e. PMC, Federal, Lake City, and even Prvi Partisan. I bought a case of 1k Aguilla and didn't like it compared to the others. Quite a few dented cases, a handful of misfires, and accuracy was not that great compared to other brands. I thought I was having issues with my optic when trying to zero it (Aimpoint), and then switched from Aguilla to Federal and had it zeroed in two groups of 3.