I carry a stove and cook kit. I tend to eat breakfast in camp but catch my other meals in restaurants. I like to aim for small towns which typically have decent diners with reasonable prices. These give you an opportunity to interact with the locals. Some state parks have restaurants, so you can catch dinner at the same place you camp for the night. A lot of grocery stores have deli counters that will make you a sandwich.

Cost...hmmm...I've never even thought about cost per meal. I generally budget $30/day for touring. That will include meals, camping and incidentals.