I don't know what exactly you are looking for, if it is Military Ammo cans, you probably want to buy where you can look at it, if not, I bought two 30 cal. cans (.223) from Sportsman's guide that were pretty nice. And second you might want to check around locally. Shipping on those things suck, but the deal of the day for me was when I walked into our local ACE harware and here they were selling surplus .50 Extra Tall ammo cans for like 6.99, the exact same ones they have in Cheaper Than Dirt for 6.97 not including shipping!! So shop around, I would have never guessed they would be at ACE.
Lastly, I know this probably isn't a real popular choice given the great price of ammo cans, but MTM makes cases just plain sealed boxes, basically a plastic ammo can. Don't know about the durability, but it could be good. Also, if you wanted your ammo separated of course they make boxes just for .223 ect. Just a suggestion in case you had not looked into them. I use these kind of cases for reloading. My basic .223 range rounds I keep in .30 cal ammo cans, you can fit a bit over a case in each if I remember right.
Gundraw