Buying mixes of all kinds is very convenient.
But, it really isn’t a true money saver.

You can make up your own mixes for just about anything.
You can find them for brownies, cookies, biscuits, cocoa, or spice mixes.

You can find all-purpose cookie mixes and just change up the add-ins when you want to make them.

You can find these recipes online or in cookbooks.

I do have spice mixes-
Cajun Rub
Creole Rub,
Jerk Dry Rub,

I do plan to share recipes for more mixes in the future.

It is more fugal to buy the individual ingredients and make mixes and store them for when you want to make them.