Where can I buy the Ubuntu for Android phone dock and phone with Ubuntu on?
Like this one: http://www.ubuntu.com/phone/ubuntu-for-android
This product hasn't been finished yet to my knowledge. It's deceptive that they don't tell you this on the web-page.
Most of the focus right now is on finishing and shipping Ubuntu Touch. Ubuntu for Android is quite different from it, and is on hold right now I think.
"Ubuntu for Android, currently under development..." http://en.wikipedia.org/wiki/Ubuntu_for_Android
The 'dock' is hardware, which may be available for your phone.
Otherwise (as others have said), there is not a current / stable 'ubuntu for android' build for you to use.
Be patient ..