Using eBay's own example, if I list an item as Buy it Now for £10, the buyer will see £11.15. If the buyer then makes a Best Offer of £10, what will I see? Will eBay calculate this as an offer (to me the seller) of £8.89 so that when they add the fees back on it nets out at £10 for the buyer?
Sorry if my maths is wrong but hopefully you get the picture.