The monthly cost of taking a multivitamin everyday can depend on the cost per tablet/capsule, the container size, and the recommended serving size for the supplement. A general range for a men's multivitamin cost per day is around $0.40 to $1.20 which would cost $12 to $36 every month. Some vitamin companies or websites offer the option to subscribe to buying vitamins every month with a slightly lower cost than buying a single bottle at a time.