I get those people all the time. I always respond with "I agree, daycare is expensive. My rate is not negotiable and I feel, well worth the cost. However, I understand if my program does not fit your needs. Good luck in your daycare search. Feel free to contact me in the future should you wish to reconsider my program"

that says it all in a professional way I think but also, no wiggle room. she is emailing you numerous times to see if you will give on the cost.

Reply