The store brands are the cast offs of the quality flours. They contain more of the harder parts of the wheat and their % of gluten is irregular, changing with every batch. The grain is also irregular, containing bigger chunks instead of a fine, even grain.
If you are trying to make a quality product, every time you sub a low quality product, your final product will suffer. This goes for eggs, vanilla, sugar, milk, heavy cream, sour cream, cream cheese, etc.
One sub will not have a significant effect, but a combination of always looking for the cheapest product will result in a poor product compared to one with good quality ingredients. The same goes for constantly increasing the quality of your products. After a quest for superior ingredients, your final product will be much finer than the original.
To determine which product is right for you, you need to do some serious research concerning where you want to be in the market. If you want a mainstream demographic, you will probably need some better ingredients and some that save you money so that your prices will be geared to the mass market. You will need to experiment to find which products pack the most punch and which don't. In my opinion, the flavorings and extracts bring the most to the table, followed by the dairy. If your quality of every product becomes too low, it may be better to stick with box mixes. If your market is upper income, that demographic appreciates that quest for finer ingredients and you can charge accordingly.