Exceedingly useful. He's providing important information to the market and matching buyers and sellers who otherwise wouldn't have met each other. There was a recent Econtalk podcast with Mike Munger on this subject: http://www.econtalk.org/archives/2008/10/munger_on_middl.htm... , in which Munger and the host, Russ Roberts, discuss the role of middlemen and making markets.
Without him in the picture, buyers could have purchased their items for less and saved money.
Without him in the picture, buyers might not have found the items and wouldn't have the benefit they think buying the items at all will give them. He's doing a major public service.
Without him in the picture, buyers could have purchased their items for less and saved money.
Without him in the picture, buyers might not have found the items and wouldn't have the benefit they think buying the items at all will give them. He's doing a major public service.