Needs an explanation of the diff between right and left (and how you can use both)
This is a massive power boost!
Also, trading in, could give +1 upgrade for every full tier up of the traded in item. Since trading in legendary for basics, is a big power loss for quite a while. (Rare gives +1 to buy, Epic +2, Legendary +3, maybe have Legendary give an extra bonus upgrade for every +2?)
This would smooth out the upgrade paths! As well as give a fun minigame of getting higher legendary items for a bigger trade in later.