Am I allowed to accept a (private) 'Buy It Now' offer on EBay?

I am selling an item on ebay and have been sent a message from a user who would like to offer me a ‘buy it now’ price.
Is it within ebay regulations to accept this offer and end the bidding? I did not include a ‘buy it now’ option when I listed the item.
I have had a look at ebay rules and regulations but couldn’t see an answer.
I am assuming that as nobody has bid on the item yet, there is no reason why I cannot end the auction early.
Thank you!