John is saving to buy a new car, $4$ years from now. His bank quotes him a $6\%$ annual interest rate if he will add a new money deposit at the end of every month for the next $4$ years, the same dollar amount each month. John's goal is to have $$30,000$ in in his bank account at the end of the $4$ years. What dollar amount must he deposit each month to achieve his goal? Show your work.