When I called and made the reservation they told me it was $29.99 per adult for breakfast, $16.99 for children. The character buffet is only open during breakfast.
They have a dinner buffet, it's just not a character meal. It should cost the same as the breakfast buffet. I don't know if they do a seasonal price during the summer like the character meals do, so maybe plan for it to be $3 more if you're going after Memorial Day.