It is not recommended to purchase a monkey as a pet due to the risk of zoonotic diseases and their complex care requirements. However, if you are still determined to find one, you will likely need to go outside of your immediate vicinity. In the United States, the sale of primates is only legal in some states with a valid permit and health certifications.
It is, therefore, best to check the local regulations and speak to a licensed breeder or a pet shop in a nearby state to find out if it is possible to buy a monkey.