Hats off for trying this in Linux. I gave up on that path a long time ago and am running nine monitors with a Windows 8.1 base OS, utilizing DisplayLink USB docs in combination with the DVI out on my main doc to drive the 2560x1600 30" display (the yellow one) with all others running at 1920x1200 from DisplayLink. I then run Linux in a VM, all from a laptop whith 32GB of ram and three built in SSD's giving me a bit more than 2TB of storage.

Interestingly there appears to be an eight monitor limit total when using DisplayLink for the OS so the ninth monitor is driven from its own DisplayLink doc which I've directly hardware associated with a VM. Of course because the host OS doesn't know about that monitor I also need a second mouse so I can access it. Here's the latest photo of my setup:

aschampion

No need for a second mouse: http://synergy-project.org/

girvo

Hehehe. I once worked in an agency, where I commandeered three iMacs, and used Synergy (it may have been a similar application mind you) to use them as "monitors". Each iMac was for a different purpose :P

jacquesm

The linux version of that is called xdmx.

dfox

xdmx does slightly different thing, it allows one to build X display that uses another X displays as it's screens (everything goes through the xmdx server and last time I tried it it was incredibly slow, as in significantly slower than using normal X11 over the same network).

X11-only equivalent of synergy is for example x2x (https://github.com/dottedmag/x2x).