Hi
Although I do concur with heidilynn0_3 advice given but I also consider some facts before making the final desision...
Is this a new ebay member? (0) feedback.
Is this buyer been a member for some time? (10 feedbacks +)
You did spend some time to make up your auction then the buyer (you think has change there mind) and want to cancel the transaction or maybe they found it cheaper from another seller on ebay and is bidding on it.
Now you have to spend more time to cancel the transaction and relist it.
Ebay is not a game to waste sellers time.
JMO- send a few nice worded emails to feel them out for more of the truth of their intentions, also you might want to consider putting them on your BBL (Block Bidder List)
It is your boat, you are the captain, its your desssion.