Oh, I forgot to say, to make life easier for me, as I know there is a possibility for the addon to be updated, I just made a note of the line and the change of code.
All I did was put an added change of * 1.086
Code:
ItemData.sellPriceTTC = tonumber(ItemPriceData[PreferredPrice] * 1.086)
at line 283.
So, now I see at a glance what to sell it for
Again, thanks for the tip.