I don't know about modern chromebooks, but I have an Acer C7 that I spent $199 on and then added another $240 for it to have a 128GB SSD, 16GB RAM, a working bluetooth module, and an upgraded battery. $440 total and it's been a solid dev machine running first chrubuntu and now crouton. I've mentioned before that the only issue I've had with it is lack of CPU horsepower for clojure-based work to get into the REPL, which as I understand, is slightly fixed on later iterations (or other models). All of my hardware (AFAICT) works under Linux, and I use Google Hangouts, Skype, Steam (for TFC), and vim/tmux on it routinely.
And I'd still need to spend another $300 for the SSD, 16GB ram, and a new battery (batteries on used laptops are miserable, and not up to the 8 hours of usage I demand). It would also be heavier.
My battery lasts about 9 hours on a charge with normal usage (testing/developing in vim with Python (using python-mode+jedi) and Clojure (using vim-fireplace and nrepl-middleware) against Postgres, Mongo, Elasticsearch, Redis, and Storm. The original battery was somewhere in the 4-5 hour range.
