Been trying, need help. (manipulating brokerage fee displays)

[Epitech]

Ive been trying to teach myself some UI Builder things,
but i cant seem to figure out how to do this:

I want to create a modification to the player-merchant
window that will list not only the base-price the player
has set his items to be sold at, but also the prices that
will appear at the 20% and 40% brokerage fees
(and the associated actual fee)

Example:


This way, people can try to 'even out' thier prices so thier customers end up
paying the price merchants want them to pay, instead of an inflated price.

This is a photoshopped picture. My skills graphically far outweigh my XML skills.