Why buy them when you can make your own with everything YOU want?
We make our own, bought a vacuum sealer, got the good bags and make 3 meals, snacks and other stuff. Go on Youtube and look, plenty of ideas there.
If you go hiking or camping they are awesome and take up much less space! Make sure to date them as well.
The gun show in your town (the one on the north end of town forgot the venue)
Everytime I have been there someone has individual packages and/or cases for sale.
Most if not all I have seen are marked "not for sale" govt property, but they are "always" available. (price is between 40-50 bucks a case that I have seen)
Brians Surplus usually has them in stock, but they are priced along the same lines as the rest of his stuff.
When I used to live in Bedford the surplus store there had them for $7 each.. bought a lot of them as a kid for camping.