I worked for one of the largest paint companies in the world for a bit over 8 years, specifically in their automotive division and I can tell you exactly what is in the paint you're spraying.

From whatever your chosen paint company's top tier line, to the next one down, there is zero, or near zero difference in the paint.

Go to the next one down, and the most likely difference is a lower solids content - which just means you might need more coats to cover. Once the solvents are gone, you're still left with the same thing as the higher cost product.

All your additives? ... reducers, hardeners ... most of them are made by a few different companies and labeled for each paint company. Of the 20 different reducers sold by your favorite paint company, all of them are likely 1 of 2 different things, and the only difference between the expensive reducer and the cheaper is the label.

We had extra labels for a lot of our products, so if we ran out of something, we could change a label and ... Poof! ... we're not out of it anymore!