[Baertram]

Hello,

the lists normally are some ZO_SortScrollList controls. If you check the source code of them in the esoui source code you get a basic understanding for them (I hope).
Or maybr the forums here or the wiki got some info about them as well.

Normally those lists got a setup function for each "row" of the list which you can use to add controls to them.
Addons like ItemSaver also got some hooks where they add controls to lists if the rows get created:

local listView = PLAYER_INVENTORY.inventories[INVENTORY_BAGPACK].listView
        if listView and listView.dataTypes and listView.dataTypes[1] then
            local hookedFunctions = listView.dataTypes[1].setupCallback
 
            listView.dataTypes[1].setupCallback =
            function(rowControl, slot)
                --Call original function of the row
                hookedFunctions(rowControl, slot)
 
                --Do not execute if horse is changed
                if SCENE_MANAGER:GetCurrentScene() ~= STABLES_SCENE then
                   --Do your stuff here
                end
            end
        end

The prices should be either in the rowControl.dataEntry.data table or there might be API functions (check the API documentation inside the Wiki for current API 100028) which are able to be used with bagId and slotIndex, or itemLink, of the rowControl (the item).