It is easy to make your own mixes. I cheated and got a book to get me started. It is a great book and makes it easy to make your own convenience foods that have the ingredients you want in them and save a lot of money. The book is called, "Make-A-Mix". It is just wonderful. I ordered mine online, but you can get it from bookstores too.
There is an amazing selection of mixes in this book for all sorts of foods. Once you read it a little, it will probably inspire you to make up some of your own mixes.
A way to get started is to look at your favorite recipe. Separate the dry ingredients from the wet ones. You can mix together most dry ingredients ahead of time. You need to know how much of your mix to use for one batch. You can make enough dry mix to make the dish one time or make a lot of it to use for a week or a month or several.
There are some dehydrated foods that you can buy from preparedness storage companies that are especially good for making your own mixes. Some of my favorites are, powdered eggs, powdered butter and powdered cheese. You can use these in your mixes and end up only needing to add water for some of them.
You already know you can get powdered milk from the regular grocery store, but it is often cheaper when you buy it in bulk. Powdered milk makes mix making easy. One of the easy ones that I especially like is cocoa drink mix. It is a lot cheaper than buying it already made.
You can use powdered milk to make whipped topping. You can add extra sweetening or not; your choice.
Something you may not already know is that not all powdered milks are alike. Most are low fat, but you can get them made from whole milk. These are not low fat and taste more like fresh whole milk when you add water and let them sit in the refrigerator for a while.
The mix that I use the most from Make-A-Mix is the biscuit mix. I use whole wheat flour to make mine. I do not like the taste or texture of white flour biscuits much.
I make my own pizza dough without any change in the biscuit recipe. Instead of making biscuits I just roll the dough out onto a lightly greased pan. I brush the dough with oil so that it will brown nicely and not get soggy when I add toppings. I bake the dough and then take it out and add already cooked toppings and cheese.
I make extra pizzas like this and freeze them for convenience foods and emergency storage as well. I cut them into individual servings and put them in plastic containers or zip lock bags. If I want to use zip lock bags, I freeze the pizza, already sliced on the cooking sheet and put them in the bags already frozen. They handle easier that way.
I am especially terrible about eating up my frozen pizza food storage. I love the stuff and it is so easy. I take it out and thaw it. Sometimes I eat it without even warming it up. It works great for writing blog posts, for example. I can easily eat and type at the same time. Sure it is disgusting, but nice for me anyway. It gets my writing done.