When you consider that meals in the freezer section cost $7-8, need freezing and normally microwaving to heat, or thawed before cooking in an oven of some kind, these meals are not that expensive.
However, I sometimes use a "Shuttlechef" (SC) thermal cooker, I can do a Thai curry or beef stew for < less than $20 each which makes 5 meals in each batch. That's $4 a meal. If I cook one on day 1 and eat 1 of them, I freeze the other 4. Then on day 2, I cook a different meal, eat 1 and freeze the rest, that's now 10 days of eating for 2 days cooking (and it's easy, I'm no chef when it comes to the kitchen) at a cost of a bit over $30 compared with at least $110 for the above.
Yes I do need to freeze, I have a freezer in the van, but I eat at near a 1/4 the cost and get to chose every ingredient.
I don't have to eat them all at once, I can still mix SCs meals with other food.
I guess where these meals come into their own, is if you have no freezer, maybe camping in swags and tents and too far from civilisation for a pub meal.
PS example SC meal - dice some beef (cheap cut), brown the meat in the SC pot, add stock from a carton, a little gravy powder and cornflour if you want the gravy thicker, salt and pepper to taste, diced potatoes, sliced carrots, until the pot is nearly full. Bring to the boil, then simmer for 30minutes. Add a can of peas if you like them, put the lid on and then put the whole lot into the thermal outer and place where in won't get knocked around. You do all of this at breakfast, when you get where you are going or at the end of a day detecting, the stored heat has cooked through and the meat is most tender I have ever eaten. After a feed, let the rest cool, put the meals into disposable Glad containers and freeze. Easy