Garthanos
Arcadian Knight
I am picturing Loki knowing what to trade for what not just the buying influence cheaply. Hmmmm "Finding the Perfect Price". It could be a story vehicle for the sequential item quest line perhaps could be leveraged into McGuffin some times.
It occurs to me when something is being used directly as a story vehicle it should be handled as a skill challenge or similar and when its luster isnt so central and it has become par for the course let it simply be a practice.