Originally Posted by Pharaoh

If you are implying that the cheapest paint should be used, note that some qualities of paint (in particular dried weight and surface characteristics) are proportional to cost. Very similar to bottom paint on a boat (although different characteristics are applicable).

Also, skill is involved in removal of old paint, surface preparation, and priming.

Spend a few more dollars on better paint and labor. Get more in return due to lower fuel costs over the lifetime of the surface.