Negative FeedBack-PointLess

Yea Just got my first negative feedback on a buyer that was really pointless. So I listed a auction of 15 Baseball Cards, but in my auction I wrote down buy it now for .99 per Card. I even stated saying that if a card was sold, I would even edit the listing to mark it has sold. So a buyer had bought my listing, and he asked if he could get all 15 Cards for a price of .99 plus shipping. I messaged him and explained to him about my auction and how I stated .99 per Card. So he got mad & got butt hurt about it and gave me a negative feedback on somthing he could of fixed himself. By the way, I was even nice enough to refund his money before he even asked. So please people was I wrong as a seller or was the buyer just trying to rip me off? Please post your comments.