A good source of cheap drama in the campaign.
Game and Story Use
I can see using an auctioneer to set up a scene and introduce an NPC who I want the party to have sympathy towards (the poor widow, having her farm placed on the auction block). Alternatively, the auction can be a showdown between two rival economic predators (ranchers, land owners, business people) for control of a prized asset. We could introduce it as the climax of the campaign, with considerable sneaking around and dirty tricks prior to the big event as the two rivals jockey for information and advantage. And the prize (what is being auctioned)… may not be a prize after all….