Another thing you could look into is vinyl wrapping it. I paint for a living and if you want to keep cost down they can do amazing things with vinyl. Sometimes they make it hard to compete with,but a paint job will last long due to it being sealed (clearcoat). But either way i definately recommend getting something over the rust before it makes a mess because if you want to long to put something (paint or vinyl) it will pit on you and make things a whole lot worse. Just my opinion