Well I guess he/she is doing a service.
All he is doing is listing the completed bids, showing how much the seller wanted, how much he got. He does this for highest and lowest bid and then does an average of them.

I guess if you have $19 to give away it would be a good reference sheet. But myself, I don’t trust others research, I do it my self. I also feel this takes the fun out of collecting relying on others work. The collector should do the legwork himself. The New millennium collector can pull up completed sales on ebay and follow what ever he wants to keep track off. When I decided I was going to buy my windows pro XP from ebay I took one month of studying compled bids and researched the product by reading the sellers description. After a month I felt ready and had a reasonable plan of nabbing a good deal and a good product. And I did.