It would be simpler to set up a Fixed Price listing for the customer.
Use his name as the title to make it difficult for anyone but him to find it.
Correct the asking price and leave the shipping as is.
Tell him what you have done and give a deadline.
When he bids, the FP listing ends and you proceed as usual.
If he does not meet the deadline (you 'd be surprised how many of these are not completed) add him to your Blocked Bidder List and change the title back to the original, modifying the price if you want to.