Rockbox-theme-classic-v2 is a project mainly written in ..., it's free.
A Rockbox Theme for the Sansa Clip+
1) Install Rockbox on your Sansa Clip+ by downloading
from here: http://www.rockbox.org/download/.
2) Now you can install the "classic-v2" theme by downloading the .zip
from here: https://github.com/skratchdot/rockbox-theme-classic-v2.