When shopping for your next paint color make sure you buy a premium brand of paint, not just whatever is the cheapest.
Why?
Cheap paint is inferior in every way to premium mixtures — you will need multiple coats to get the same coverage, the durability is not as good, and you will need to re-paint more often.
According to some tests I’ve seen, Kilz Casual Colors paints from Walmart is an excellent choice when it comes to painting interior rooms. Kilz is scrubbable, stain-resistant, and very durable with just one coat. The last time I bought some it was about $25 a gallon — a bargain price for a premium brand of paint.