Why are some beans only available for a "limited time"?

為甚麼有些豆子只能「期間限定」?

The coffee expert who collaborates with Douzi has some influence in the industry, and the green bean supplier is also a long-time friend. So, whenever there are seasonal, top-quality beans available, he always manages to get his hands on them first. I, this little bean, am fortunate enough to get a small share from him to share with everyone. Therefore, some beans are truly rare finds, with limited quantities. Once they're sold out, they're gone. If you want to try them again, you'll have to rely on fate.