If we create a tournament-ish market event, I think we should indeed make sure that trading remains an oral occupation. Having NPC's automatically assign deals somehow would not be any improvement. And not encourage RP either.
I do think we should encorporate the trader's skill, though. Perhaps Traders with higher trader skill are able to place a bid before others?
Also, I must concur that we can doubt the idea of how 'noble' those local fairs would be. But then again, trading itself is already violating that line, I believe. Most medieval trading was done by a middle-class, something we lack in BM. (not saying we should add it in
Lastly, I even think adventurers could somehow find a place in those. Selling Unique Items to nobles, or common items to each other, perhaps? (but that's just a loose idea.)