There are two currencies,...

There are two currencies, Dining Dollars and Meal Swipes. Dining Dollars are usable at either the Greenery buffet, the POD market, or the Drop. Meal Swipes are only usable at the Greenery buffet. 
Access to the Greenery (equivalent to a Meal Swipe) can be purchased using Dining Dollars at the following rates: Breakfast $12.73, Lunch $14.88, Dinner $16.34.