Since no one has actually explained this fully I will.
Previously the "Market" button was know as Dealfinder and some of the older members still refer to the "Market" as dealfinder. Essentially there was a feature on the old version where it gave you a list of items that were on sale (Forces, relaxes, emotes, trails all on one page). The items were represented by a percent that told you how far or below the Torishop and item was.
The mixed list of items is now gone but you can still search items specifically. If you would like to sell an item you can click on the image and it will open a new page where you can give it a price. And hopefully in time it will sell. If you still can't find the link to get to it use
this.