You don't have to buy expensive gifts. However, we encourage you to find out what your host parents and host children like and give them something with a personal touch. This could e.g. be something typical of your region. If you are going to the US and you are under the age of 21, the gifts should never contain alcohol (wine, chocolates with alcohol, etc.). Gifts are often opened at the security checkpoints at the airport, so don't wrap them up too much.