Sarah wants to save for her daughter's college. Her daughter is $3$ years old and Sarah anticipates to send her to school at age $18$ for $4$ years. Current college costs are $$15,000/$yr$.$ Sarah anticipates a $4\%$ inflation rate on college costs and believes she can earn $7\%$ on her college savings investments. How much would Sarah have to save AT THE END OF EACH MONTH to send her daughter to college?