Or Rares and nymphs wouldnt appear in the bazaar.... just like they dont now, and the upgrade button would still be there... just like it is now.
Im picturing it more like this.
After you beat the quests, there is a button that says "Buy Upgraded Cards" in the bazaar. This button would replace the bazaar with all upgraded cards. Then you could from there push a button that says "Buy Regular Cards" The upgraded cards would be worth 1500 + ard Value, just like they are now.
This would just save the trouble of
1)Buy a card
2)Leave Bazaar
3)Upgrade the card
Makes it a lot simpler. Its amazing how many people come here with the sole intention of shooting down ideas. I think the OP thought it was pretty obvious that cards that arent in the bazaar would not be there still. And he never said to get rid of the upgrade button. That would be a stupid idea. Say I have 7 horned frogs. If the upgrade button was gone, then I would have to sell my 7th frog and then buy a Giant frog right from the bazaar. It wouldnt make sense to remove the upgrade button.