I always get my 762 from cabelas. Wait for a free shipping event.
For 9mm, theres a great deal for the RWS brass cased stuff from a forum sponser, cant remember the name. Some of the best 9mm Ive shot, and an awesome price right now.
I'll second that, while maybe not as cheap as some online sources; Alamo Ammo is local (always good to help the local gun community) and it's nice to be able to "cash & carry." I've bought some Yugo 7.62x39 (1260 rounds in the crate for $225) from them as well as 7.62x54R, and they've always been great to deal with. They even gave me a free "spam can opener" for a buddy at a show because I had bought from them before. I find using them to be a "win-win" situation...