Monkeys' diets vary depending on their species and environment. On average, a monkey will need to eat about 1-2 cups of food per day. This can include a variety of fruits, vegetables, nuts, seeds, and insects. The cost of feeding a monkey will vary depending on the types of food you purchase and the portion sizes. In general, you can expect to spend around $20-$30 per month to feed a monkey. However, this cost may be higher or lower depending on the type of monkey and its dietary needs.