DarkAGeS, two more points: sell and buy volumes are much less then common khS volume you can find at status page and khS price decreased from 0.0015 btc/khS to 0.0007 btc/khS during last 2 months.

So scrypt.cc can sell some khS 2 months ago and buy it back now, the profit in this case is much more then mining profit.) They can decrease or increase price at any moment, because they have more khS and btc then all their users.

Yes, it is almost Ponzi, but still can be profitable for users too.)