You can get the soda cards at any bar. But just to let you know it is not for cans of soda it is for a glass which they water down with a town of ice so you have to make about 10 trips to the bar.
What I did since I am not a drinker is bought one of the water bottles that are insulated to keep cold and kept pouring the soda in there so I did not have to go to a bar every five minutes.