OptiX

OptiX is the last shop with the best Bitcoin farming cards. It's a white building with no windows and an enormous "OptiX" sign on it. The "OptiX" sign is black, with a small light effect surrounding it. You can buy 7 cards in there. To get to OptiX, you have to enter the Level 200 area, enter the train and exit the station. Then take the left path until you reach it.