Allow trade-ins for different skins at a reduced gem price.
I already have two sets of unlimited-use-gathering-tools but would like to get different looks.
Since I already have two sets of them, there is no need for me to get a different set but I would if I could trade some in and pay 250 or 500 gems instead of the full 1000 gem price.
We get the choice and you get the gem purchases.