Just released an update to the "Economy" page of GR
now after each SDB and Auctions table, there is a list of the last 50 sales. Showing each price, the quantity and the time the sale was made. This helps to see what's going on "right now" on that specific item, including the quantity used on each sale.
and now, if you search for a furniture items (this is the best I could do with the data the API is showing at this moment), you can see a list of sales for that furniture item. the thing is that it is showing all furniture items, with or without an upgrade. that means that if you search for "Discrete Ceiling Lamp"... it will show all "Ceiling Lamp" upgrades...
note: as soon as the API allows to show the specific furniture item... I will change it of course.