These are the sites I follow regularly for ammo stocked by various dealers. Some of these are right on the money, others tend to be a bit behind.
1) Already mentioned, but my favorite is http://www.wikiarms.com/?utm_source=Tactical+Republic&utm_medium=Banner&utm_campaign=Tactical+Republic“>
Of course, several Shooting supplies websites have the ability for you to sign up for “in stock” notifications. So be sure to take advantage of those also. Hope this helps. Works for me.