http://www.crownpt.com/TrayPaks.htm Crown point seems to be a commercial vendor for Sopakco. I just found that they offer the squad tray packs. These serve 9 to 18 people per tray.
Longlife Foods This is a source for various ration and emergency food products.
Meyer's custom Supply A good selection of freeze dried and long term packed foods. They have Alpine Aire.
Emergency Essentials Be prepared seems to offer some alternative packaging options for what might just be a standard MRE.
ARE YOU PREPARED? This site offers both Mountain House and Alpine Aire.
MREinfo.com This is a fairly informative site that has good information about the mil-spec MRE and other rations packages.
Wikipedia page on field rations. This includes information about rations from around the world and links to other info.