It might be because of postage...Always on Make An Offer, so you "Make an offer" which is refused and usually save around 30p! Lol, I still can't work out the idea of Make Offer if folk aren't prepared to drop the price, must be missing something.
For example there is something I sell on ebay with free second class postage that is £4.99. I regularly have purchasers who want more than one. The item weighs virtually nothing so there are no additional costs to me whether I sell the customer 1 or 50, The postage and packing remains exactly the same.
This will normally increase my profit by around about £1.00-1.50 if the purchaser does not make an offer. If they do I can always come down without losing out on my profits.