Lets say, bfp is removed. And a player find a ultra rare card for 100 gold, and 100 gold is like 1 hours of playing lets say. That just a mistake of the guys selling the card.
You can't block someone selling a ultra rare card at a bad price.
And remember most player sell their card on "Gold/hr, Rarity, Power", so if you can gain 50gold per hour for a decent player. A good card will probably be around 700 gold.
And if you can get more then that, let's say 150 gold. The card will be around 4000. (Number are example, i didn't do any math. It's just to get the point)
And upgrade should cost the same for every card. Because as a dev point of view, there is no card more powerful then other. They are all card. The player define the power of a card. Dev just make card.
( 1 Upgrade = 100 gold; 2 Upgrade = 300 gold; 3 Upgrade = 1000 gold; Example number again)
And yeah, we should remove from our head the cost of card on the real game. Because we are not going to have the same reward system.
Capping the money gain per day, is just a horrible decision imo. And i'm sad some recent game use it.
Because it's like, saying to the player "Yo dude stop playing our games, since you play too much and you love the game, we are gonna block you for getting anymore money !"
Some player can find it bad to see other player go really fast.
But as a dev pov, why should i give the same reward to a player that only play my game for 1 hours, and the other that play it 10 hours ?? You get my point.