I'm not too sure why, but I think it would be kind of neat and possibly beneficial to have a graph or something similar that shows the amount of an item that is being bought, how often, and for how much it's being bought for.
Something similar to how the Steam market for Skins, etc work. It shows how many of that item is being sold per day, and what price. It also somewhat shows whether or not that specific item is decreasing in value over time, or increasing in value.
This wouldn't be something that would be absolutely required, but I think it would give us "number crazy" people who just like statistics and likes to see what's going on with the market, etc would make for a nice addition.

This may also help new coming marketeers on finding out which items they should invest in buying and reselling depending on how popular those items are and how much they sell for.

this would stop people from getting ripped off, i bought a 512 set for 450k a couple of months ago and this woulda really helped.