I've been studying the Lenovo Ideapad 100S, very slim, very light, very cheap at $200.
Drawbacks; just 2G ram(ya don't really need more for the applications mentioned), and smallish ssd drive (64G), and just USB 2 ports.(a little bit slow)
But you can use the extra micro ssd slot or an external drive.
Advantages; Lenovo machines are quality kit, cheap price, and very portable.
Lenovo Ideapad 100S - Full Review and Benchmarks