selling item after ending auction

Hi everyone,

                     I have an item for sale (a 3 book pack) Two buyers want me to separate the books. 1 buyer asked if I could lower price and add an buy it now button to the listing, lower price because they didn't want all three. After contacting customer care found out I could not add the button mid auction. I msg them this info. Got an msg back asking me to cancel the listing, then they would come pick up the book. Isn't this trading outside ebay. I thought this wasn't ok.

Thank you in advance