Regarding buying points for ridiculous prices, they may well be of criminal nature. iTunes cards were at ridiculous prices and people who bought them sometimes got bitten later, even though they worked at first. The scam was that they were bought with stolen credit cards. If the card got reported, then they'd find out that the points were purchased with a stolen card and then Apple would remove your account. In addition to that, buying the points essentially meant that you had, wittingly or not, supported the crime of stealing credit card numbers. Some day you could well get bitten by *that* due to making the stealing of credit cards easily profitable.
So... if the price seems too good to be true on ebay, odds are it *is* too good to be true. Even if you never see any direct consequences to your account, you are supporting criminal activity.