For those getting the 'happy' message instead of the price, this is because in order to find out the price of a pet, you must not have the full money out of the bank that could buy it with.
The code must check how much money you have to adopt with, how much the pet is worth, then if you have the money avaliable to buy, then check to see if the pet is avaliable. If you don't have the money, then display the message telling you how much you would need to adopt.
If you're getting the happy message, then put all your points into the bank and try again.