Why not put a price on it and advertise it here? I am sure I am not the only member here who often dreams of having a second battery. Ebay does no one any favours, paypal neither, often the fees make the transaction impractical for vendor & purchaser alike.
At the right price I could be tempted out of South Yorkshire into North Yorkshire to collect saving you lots of hassle and fees, I bet I am not the only one. You have to accept though that some people, as you once pointed out to me directly, prefer to not buy second hand and value a warranty & local service above the discounted price.