From memory, I think dinner was like $26.99. I remember it was a few dollars more than WDW buffet dinners (character or not). Goofy's price did include the tip though. So that would even the amount out some. I don't recall the breakfast or lunch price. But I'm pretty sure they were under $20.
I think Goofy's serves breakfast, lunch, and dinner (all character meals). We've had dinner and lunch and found lunch to be better (value and food selection/quality).