The game has a stock market like berry market. There are five kinds of berries in the game: Blackberries, Blueberries, Cranberries, Raspberries and Strawberries. The prices you will get for them will change every day. In order to get them you can grow the bushes yourself by buying seedlings, which are 100 Ritch per seedling, from Daisy. According to her you should leave plenty of space between them when you grow them and there should be no weeds or grass around them. Once berries grow on a bush, they will stay there for three days, then fall off and turn rotten the next day.
Charlie from Charlies Noodles will give you the recent price changes for every kind by giving you the prices for the last three days. These prices refer to the ritch you will get by selling them to Cat Sith when he is in the haunted house. If you sell them to Malila of The Emporium, you will only get 30 Ritch per Berry, no matter the current price at the market. Charlie can also predict the price changes for a fee. Asking him for a prediction will give you 3 choices: 100 Ritch, 500 Ritch and 1000 Ritch prediction.
Berries will go bad after a certain time if you don't sell them, however you can keep them in your Magic Chest (any container you can place in your room) for as long as you'd like without them turning rotten.