I don't have the faintest idea how it comes out cost wise to purchase a soda card versus buying a glass outright. I personally think you'd have to drink lots and lots of soda to make up the cost of a soda card. With that being said, I do know ppl who have purchased them on board, but they drink soda for breakfast, lunch and dinner and all through the day and night. For those heavy soda drinkers, maybe the card is worth it. For us, and maybe for you Colleen, bringing on a 6-pack or 2 may be the ticket !