What I don't "understand" is why someone wants to buy an account (of such type) when he can open one in a matter of minutes and add whatever amount of funds he likes.
It may happen for various reason mainly to scam people or to get few extra money. For example getting 300$ by 100$ is too much profitable. You cant get 300$ by depositing 100$. Hence there might have deposit fee which we have to pay to the site or to the bank which allowed our card or any other payment gateway.