Lenovo is about to release their new line of thinkpads. For the first time, most of them are going to have 1080p IPS screens. Historically, they have supported Linux better than most other manufacturers. Keep an eye out for the T440p, T440s, and the x240, they are all going to be around your price range, and they should be really good machines.
The Macbook Air is another good option, unless you truly do need that much power.
If you are going for power, the Asus N550JV is still a much better option than the HP. It's got a metal chassis, a Quad Core i7 Haswell processor, a 1080p IPS panel, and a Nvidia GT 750M. The best part is that it costs about the same as the one that you were looking at.
If you want something cheaper, I'd keep watching the Lenovo Outlet. I just bought a T430 with 8GB Ram and a 256GB SSD for 448 on the outlet, you just have to be patient.
I think you need to understand better your needs...
1. Solid state drive. One of the few upgrades you'll notice day to day.
2. Portability, and screen size. After a handful of laptops, I've settled with a Samsung Series 9, 13.3", 2.8lbs. I'm constantly on the road, so it works perfect. If I'm home, I just HDMI the display to my 24" monitor and keep working.
3. Display. The Samsung I'm running uses PLS, similar to IPS, so it doesn't matter if you view it head on, or any angle, the colors and lightness remain accurate. This is incredibly important for any type of design work, and on my prior TN laptops, I'd be bending my screen forwards and back, trying to dial in subtle differences in color.