First post here. This seems like an old thread but I think I found a solution to do EXACTLY what you are talking about.
Get a USB 10-port hub and get 6 USB to DVI converters. I have only done that with 2, but I think I read it should support up to 6. Not sure if it will be fast enough with 6 monitors, there are USB 3.0 solutions that might be better. I had no problem doing 2 and was shocked that I was even able to watch YouTube videos on it.