How much does a Flexible OLED Rolltop computer cost?

There is no such thing. It's purely a concept. OLED technology is used purely for displays and TVs at the moment. Samsung are making great strides in the OLED display market, with a 55" flexible screen featured at CES 2012. Prices for production models are expected to be in the region of $8000 or more at the time of writing, although that will drop as the technology is mass produced. Smaller OLEDs are already appearing in handheld devices. But the rolltop computer itself is impossible until someone figures out how to roll up a battery to power it.