Basically the only one making money is ebay. There are so many sellers selling the same products that the sellers are dropping their prices. Buyers can do well tho. The fees ebay tacks on add up rapidly and then you have to figure in the fees for paypal and other payment methods.
Also, it is if a buyer complains you are out of luck and have to refund the money to them. I sold on ebay for years and did quite well. But like many sellers, I quit due to all the fee changes, feedback changes and the lack of respect for the seller.
The last time I put books on to sell, I made a whopping $5 and ended up owing ebay $15.
Too much competition and too high on the ebay fees. Buyers are getting wise to the fact that sellers can not give negative or neutral feedback to them and many take unfair advantage of that.