I have found such foods to be cheaper than fresh food. I went on a diet using prepackaged meals, and have managed to lose 25 pounds over a couple of months with few problems. I also found that my food bill was cut almost in half versus what I normally bought, even including the fresh fruit and veg I buy to supplement the prepackaged material.
Industrialization is a wonderful thing--makes the great bulk of food cheaper than taking the time to make it yourself. This has freed up a lot of time in my family, so we are able to get a lot more done over the course of a day.
The problem is that the WRONG packaged foods will free up a whole lot of time (by helping you die much quicker). I'm not a health nut, but the amount of sodium in some packaged and restaurant foods is astounding. Some contain two or three times the sodium you should have in a day. The amount of fat in other foods is even worse, and certain foods don't do well being frozen, while others thrive. Like everything else, it's just important to glance at what you're going to buy before you buy it.
If packaged foods cuts your food bill in half, by the way, you were doing something terribly wrong. Eating fresh cuts my food bill in half and then some

Buying bulk when it's on sale (chicken and pork freeze exceptionally well), preparing vegetables and fruit properly (salsa keeps better, for instance, than just tomatoes; marinara sauce jars well or freezes in containers; soups can keep for a very long time in a freezer; pie fillings and ice cream toppings can be made ahead of time with fruit that is on the verge of being overripe and headed towards spoiling), and making as much use of every part of what you buy (bones for stock, stale bread for stuffing cubes/breadcrumbs, citrus peels for zest and potpurri, etc.) can go a very long way.
I also make my own microwave meals

They're delicious and usually only use a little pasta, or a tiny bit of meat, or a handful of vegetables, which is great because that's usually what's left out of a package. It's a great way to use the little bits left over.
Anyhow, I hope you checked the sodium on your packaged meals, and if it's high please consider having a banana and ensure you drink enough water. Just friendly advice.