Could be implemented as either a premium feature or not.
The premium feature version:
Gives access to graphs of the mean price up to 1 month down to maybe an hour.
The non premium:
Just displays the mean of the item during the 72 hour period
Ways I thought I could be exploited:
Is artificially listing for low price and buying up on alt. This could be fixed by having it calculate the mean on how long it was spent at the lowest price
Pros:
New players can list the item for mean maybe as a quick list feature that auto sets it at mean?
Reduces effectiveness of buying out market
Cons:
Makes it harder to manipulate market
Any thoughts?