Regardless of anyone being "wrong" or "right", it is standard practice on eBay with pick-up items to Buy It Now, then inspect and pay on pick-up.

No one in their right mind would pay without inspecting a pick-up mind, and I see you don't expect that...unless they've hit the BIN option, but people do it this way so that no one else BINs the item while they are in the process of inspecting it, thus (formally) having no claim on it if they actually want to purchase.

The format conducive to the way you want to sell (Classified [with best offer], where the sale wouldn't occur until agreed upon by both buyer and seller) no longer exists, so you are actually going to have to find a way to compromise between the way you think things should be done, and the way the majority of buyers are used to things being done.