Are there any options for paid support of Roundcube installation and configuration?
I could not find anything on the web site.
There is no official paid support for RoundCube. If you need RoundCube installed or custom work done there are freelancers that will support it. Feel free to contact me at scott [at] skaero.com to discuses what you need done.
Kolab Systems AG provides paid support for Roundcube too. See http://kolabsys.com.