Please help me with this question! Thank you!

Homeowner's Association (HOA) Fee

Assuming that you are required to pay $300 monthly HOA fee. Current bank's savings rate is 5%. If you want to keep the property for 10 years (120 months), how much of the hidden cost (burden) you will be carrying should you ignore to calculate it out and to negotiate with the seller?

{Note: Hidden cost (burden) is the one you did not realize when you bought the house but later on realized that it actually comes out of your pocket. It was "hidden" from the seller.}