The recently announced Sigma 100-400mm f/5-6.3 DG OS HSM lens is now available for pre-order for $799, which (as predicted) is substantially less than the comparable Canon models. It is available for Canon, Nikon and Sigma mounts and is expect to ship in late May. Check it out here at B&H Photo.
The new Sony A6300 started shipping today. B&H confirms that pre-orders have started going out to customers and will continue to fill orders as new stock arrives.