I've had chickens for about 2 years now. I keep them mostly penned up for the entire garden season. When I do let them out during garden season it is right before dark so I can keep them away from the tomatoes and other vulnerable plants.
Otherwise, I let them out pretty much all day on the weekends. My wife is home with the kids during the week, and they let the chickens out occassionally if they're outside and the weather is nice.
I am able to sell all our excess eggs for $1.50/dozen. I think they are worth more than that, but my mom sells them to her friends at work, so it's easy for me to do it that way and get a bit less. I'm not in it for the money though, I enjoy having them around. I would not ever be without a rooster. I love hearing him crow and watching his antics. He's barely audible in the house with the windows up. Even with the windows down in the spring and fall, he's still not as loud as my beagles when they start barking at something.