I think eBay is a case of everyone wanting and expecting things for 99p with free postage. Sellers are obliging by listing things that are worth what the buyer is prepared to pay. Fees, shipping and HMRC take a huge chunk out of a small sale.
A dozen or more years ago when the British listings typically numbered about 3000 at any one time, the number of quality items was as many as are listed now. The down side is that current listings are well over 100000, so the dilution of quality is certainly 30-fold and probably more. Most people have a life. From a personal viewpoint, I only look if a customer is asking for a specific item, otherwise I can't be a***d.