"Cheap" paint is really expensive.
The reason is simple: cheap paint doesn't cover as well, so you have to put down multiple coats. That means it takes multiple cans of cheap paint to do the same job as one can of higher quality paint... not to mention more work for the painter.
(By the way, primer is a different story. Unlike wall paint, it's supposed to go on thin, and good primer is often translucent.)
Brand matters, too. I once bought a rather expensive paint which turned out to be awful. I had to put on two full coats... even though I was just painting white over white! (The old white was slightly yellower and kept showing through.)
It turned out well in the end... but only after a lot of patience.
So which paint should you buy? My two favorite brands are:
1) Benjamin Moore's Regal series
2) Sherwin Williams's Infinity series (available at Lowe's Home Improvement stores)
#1 adheres so well that it's even hard to peel it off the metal ferrule of my brush! Wow!
Once you choose the right paint color... and the right paint... it's time to choose the right painter for the job. If you live in Asheville, give us a call. We love this stuff!