I'm presuming it's for your lovely cooker and the offer is less than £350 but more than your opening auction price £250?
Revise the item adding s Best Offer option or:
What you can do is to revise the auction to the price agreed, click on the item top left >> Revise item. You can do this as long as there are no bids.
Ask your buyer to bid.
On the Seller hub ( link below if you're not already on it) tick the little box left of the item scroll up to Actions. From there select End item to Highest Bidder.
This will sell the item to the buyer for that agreed price, and you then await their payment before exchanging contact details for collection.
Seller Hub here:
https://www.ebay.co.uk/sh/ovw
@johnxj900
