You couldn't buy that volume of shares on the open market for...

You couldn't buy that volume of shares on the open market for two reasons. The first is, there simply isn't that volume available to buy on the open market. The second is that the purchase would probably be blocked because it would spike the price enormously without justification. So the only way to do it is to buy off someone willing to sell off market and at the price they'd be willing to sell. Thats my guess. But, it still doesn't explain why you'd buy at that price. You'd have to have quite a bit of confidence in the future of the company to make that kind of investment.