In reply to Denni:
difficult isn't it? I think the 'what's your lowest price' type of question, as a negotiating technique, is a wanker question.
ebay is especially bad for this and 95% of people who ask wanker questions are wankers and they don't complete on the transaction.
If you're confident of getting your price then yes, don't reply, it's up to him to up his offer, it's not up to you to bare you arse for him.
OTOH if he's serious is there a way to haul him in? Is it a collection only item? Can you save ebay fees by selling it before the auction ends?