What is the wisdom behind the prohibition of selling or buying cats, and how can one raise a cat without buying it?

It is not permissible to sell cats. The Prophet (peace be upon him) "reprimanded against the price of a dog and a cat (sinawr)," and "the Messenger of Allah (peace be upon him) forbade eating cat meat and consuming its price." The wisdom behind this prohibition is to accustom oneself to doing good deeds and giving these things away without charge. One can obtain a cat from someone who gives it away for free.