I think it would be great if you could barter for more then one item. For example if you had something worth 10 pies, you could barter for 10 pies instead of 1. I see this needed most for practicing. Perhaps when you barter with a guildmaster, you get to practice as many times as the worth of the item you traded them. It kills me everytime I trade a 40,000 copper item and get one 100 copper practice out of it.

That which does not kill us,
makes us stronger.