Apple Stores in the United States, United Kingdom and possibly other launch countries began selling Apple Watch bands as cited by MacRumors. The photo below shared by Twitter user Apple Radar shows an Apple Store in Miami selling the Sport Band in multiple colors.
Apple is selling individual Sport Bands for USD$49, while the Classic Buckle, Milanese Loop and Leather Loop retail for USD$149 each. The Modern Buckle is more expensive at USD$249 and the Link Bracelet is the most expensive Apple Watch strap available at USD$449. Apple Watch bands can also be ordered online through the Apple Online Store.