As one of its daily deals, B&H Photo Video offers the Think Tank CityWalker 10 Messenger Bag in Slate Blue, model no. 670, for $49.75 with free shipping. That's the lowest total price we could find by $4. It holds a DSLR camera and extra lens, and features a padded tablet compartment. Deal ends today.
Note: It's unclear if it will arrive in time for Christmas.