Hmmm...
Mountain House Freeze Dried. But, like you said, not cheap.
I think I saw a 5 gallon bucket of freeze dried entree for sale as an "emergency prepper" meal.
https://www.amazon.com/Emergency-Sur.../dp/B0029BE7AW
Not particularly cheap, but it might take a little while to munch through it.
Cup of Noodles?
https://www.riteaid.com/shop/nissin-...hicken-2-25-oz
Military MREs?