An etiquette question for the community: if you attend a game night at your friendly local game store, how much do you buy from the store?

Obviously, game store is not (just) hosting board games to give people a place to hang out and have fun. They are doing it to attract new customers and get people to buy games. If many people come but no one spends, the store might decide that they need to cancel the event and schedule more CCGs and minis. So how often do you buy a game at your local store to express your gratitude for the owners letting you use their space?