Timbuk2 Quickie Carry Bag- real nice!
Picked up one of these (Size Small) from amazon and it is real nice as a small tablet bag for the Prime, with full arm strap. A little pricey, but Highly recommended. Great build construction with lifetime warranty to protect the prime, and 2 side pockets for the charger and phone. It's smaller than it looks in the picture- just a little larger than the tablet itself
Insulated very well inside with well constructed bubble membrane foam, to protect the tablet from vibrations.
My Prime has a leather case and it fits great inside this bag !!! A nice compromise between a sleeve and a full size laptop bag, with still a good amount of room for charger and cable! I think the Prime with the Keyboard dock should fit nicely too!
Company link to product here!