Why do they offer such a discount? Because they need cash to pay somebody else's bill. Will there be any mugs left to pay your bills?
I have seen people in this game who paid out £35,000 one day to find there is no money in the pot a day later. Don't do it.
Maybe buy a block of 10 hours and use them up in a week but nothing beyond that. Simple rule of gambling, don't invest more than you can afford to loose!