Stick with thinkpads and checkout ThinkWiki[1] to make sure that there are no oddities you are not willing to work through on the model you want to buy.
The Dell XPS Developer Edition[2] comes with Linux installed, and has supported binary drivers from Dell. Just a little outside your price range.
I have the early '13 model with the i7-3537U processor and run Ubuntu 14.04 on it without a problem (the wireless was somewhat flaky on 13.04, but it seems better since the upgrade - unscientifically).
I had a very bad experience with a Thinkpad W series laptop (and the Lenovo RMA process). That said, I still pine for an X1 Carbon every time I see one, and the new Yoga looks reasonably well-built (the previous one was flimsy garbage).
I've got a current-gen i7 XPS 13 as my work laptop, so I haven't put Linux on it (gov't clients need Office docs grumble grumble), but I can vouch for the quality of the hardware and battery life. My linux book is an Asus with ATI graphics that gives me repeated problems, and the build quality isn't as good as the Dell. I actually find myself working in Windows more often just to use the Dell hardware. I get 6 or 7 hours of battery life with the Dell, it's lightweight, and it's quite thin. I had no trouble running Ubuntu on my previous Dell laptop, either.
Oooo, the Dell XPS Dev Edition sounds really fantastic, maybe I'll rush to the market today and get it before the thanksgiving discounts leave :P . But, I just have one little problem with Dell, I've used their hardware years ago, and to me, their customer support seemed utterly foolish(and useless), is this still true ?
While I love my X230 running Fedora, I hear really bad things about the newer X line-up, mainly about the touchpad which is apparently unusable (even under Windows), but also that they've reduced the max RAM from 16GB (X230) to 8GB. Maybe the lesson in that is to buy a second hand X230 ...
http://ark.intel.com/compare/81015,72054
I have the early '13 model with the i7-3537U processor and run Ubuntu 14.04 on it without a problem (the wireless was somewhat flaky on 13.04, but it seems better since the upgrade - unscientifically).
I had a very bad experience with a Thinkpad W series laptop (and the Lenovo RMA process). That said, I still pine for an X1 Carbon every time I see one, and the new Yoga looks reasonably well-built (the previous one was flimsy garbage).