Macbook pro retina, 13"/15" dependend on your pockets. You won't get the same quality cheaper and the battery can easily last through the entire work day. It's a productive environment, though, so if you really want to tinker with the hardware pieces, this may not be the right choice for you.
My Chromebook can run Ubuntu in a Chrome tab for 10 hours. ~350 bucks.
What do you mean run Ubuntu in a Chrome tab? Is this a full virtual machine?
He is probably using Crouton : https://github.com/dnschneid/crouton