The Nikon D5500 is now available at select retailers. As of now most configurations are in stock, with the special red color in very limited supply. A quick review of current stock shows Amazon has the best selection.

Black:
Nikon D5500 Body (Black)
Nikon D5500 with 18-55mm VR II Lens (Black)
Nikon D5500 with 18-140mm VR Lens (Black)

Red:
Red Nikon D5500 Body
Red Nikon D5500 with 18-55mm VR II Lens
Red Nikon D5500 with 18-140mm VR Lens

There are also a couple used D5500 already listed, including one used in an unboxing video at Sunset Electronics that is $100 off:
Used Nikon D5500 cameras listed at Amazon.