Seems to me the price range for lunch ran between 7 to 12 dollars. It could have been a bit lower though as my memory doesn't always serve me well these days. Really good food there though and the pies are all home made right there. Very yummie.
They do have a new dining area that is in the actual cavern. Those are the prices for that dining area. Up in the regular restaurant area though the price is much lower. By the way, if you do eat in the actual cavern, the price of lunch or dinner includes a tour of the caverns. Personally I'd rather eat upstairs in the regular restaurant area.
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