I know when we couldn't get IMP's through the system we used to get a civilian version of the MRE (slightly smaller than the military ones) from a company call MREDepot. I think they still have a web site to order from but I haven't dealt with them in a couple years, try http://www.mredepot.ca. I am not sure if you have to be a purchassing agent or a large group to order there though. For my personal use, I have bought some from Forest City Surplus in the past. They have the US Military MRE's, and its generally not old stock near the end of their shelf life. I've never had any problems there, but their stock varies as to what meals are actually available and how much they have on hand.
If you are just looking for other meals by brand name you should try HotPack Meals. The quality of the food is excellent and you get a bit morein the meal bag than in the standard US main meal bag. It is a british company with a Canadian Subsidiary. They had an ad on one of the adventure racing sites in the past, but I can't find the link. Got a free one at a race about a year ago and it was pretty good, filling and tasty. Not sure if they have a web site or where to buy them but it is a name you can google. Beyond that, you should try IRL Supplies in BC. They sell a boil in bag meal (action meal I believe they market them as). I bought a case of them last summer for my camping/trekking and it was pretty decent (limited menu but okay quality). Their site is http://www.irl.bc.ca
Hope this helps.