For a limited time Adorama is selling the Brenthaven Collins Slim Briefcase (indigo) for only $39.99 + Free Shipping (tax only in NY and NJ). This is $60 off the list price of $100, and Amazon is selling the same bag for $100.

This bag will hold a 15" laptop, and comes with a protection system that wraps the laptop in a high-density foam. It's durable, and Amazon reviewers love it.