MSI Wind U100-053US (6-cell battery version) in black is available on 
for $479.99 (After $50 After a delay due to problems with supply chain, MSI is finally starting to ship Wind notebook with a larger, longer-lasting 6-cell battery.
Several online stores started offering MSI Wind laptop with 6-cell battery for pre-order. This option adds $50 to the price, making the laptop cost $549.
If you are planning to travel with MSI Wind notebook, then 6-cell battery is worth the investment as it will increase the life of your laptop well beyond the about two hours you normally get with 3-cell version.