For the historic river cruise that I went on the prices are below. If you want to eat as well it's an additional $19/person, but I did not eat so I can't say if that's worth it or not. Price: Adult: $34 Child (6-12): $14 Child (5yrs & under): FREE
The buffet onboard was surprisingly good. Definitely worth the price.
Thanks! Your answer is awaiting moderation.