This mod is an implementation of sbpreise.de inside your minecraft client (fabric). The data is directly fetched from their website. This mod requires the fabric api.
The mod adds a tooltip to the items in your inventory showing their current price.
Also, there is an implementation of the website using a GUI which can be opened by pressing the key bind J
. This can easily be changed inside your minecraft settings. You can directly suggest a new price for an item via the GUI too.