The Nokia Lumia 900 is now available for pre-order. The handset features a 4.3-inch ClearBlack AMOLED display, a 1.4GHz single-core processor, 4G LTE, an 8-megapixel rear camera with Carl Zeiss optics and the Windows Phone 7.5 operating system. When the Lumia 900 launches on April 8th for $99.99, it will be one of the most affordable flagship devices AT&T has ever offered. To make this sleek smartphone even harder to resist for current AT&T customers, Walmart is already offering the device for half off — $49.99 with a new two-year agreement. For new customers, order through AT&T’s website and you’ll get your new Lumia 900 for free.