I have been to this Tiantong Temple. As far as I know, all temples can eat vegetarian food, and money can be given or not, but I have never eaten in temples. Besides, there are snacks outside Tiantong Temple, which are not expensive. There are fried noodles, a few dollars. There is also cooking, and the price depends on what you eat. If I remember correctly, it seems to be 20 to buy tickets at the temple. I hope I can help you.