It would be really cool if we can see how much dkp the item went for. This info could be in the tooltip as a list, perhaps average value or last couple of values.

Example:
opening /dkp will show everything as normal and i could search history for an item.
Additionally an item's tooltip will list its respective dkp history for that item only.

This is a wow classic request

There is an "Also won by" section in the tooltip which shows who got it when and for how much. Unfortunately there isn't a search function and you don't get this section in tooltips anywhere else -- not even in the bid frame.