Chris was right

I'm around and here is the low down on your options. First what you have been told as to the limits of the LEDWiz contacts are correct (32). You can have 10 separate RGB LEDs connected to each Wiz. One thing to think about is mutiple LEDs per each contact. For example you can have P1B1, P2B1, P3B1 & P4B1 on the same 3 contacts. You can continue this train of thought for all the action buttons for the players. Then have the player coin and start buttons connected the same way. Doing this will allow you to have room for 1 additional RGB LED connection or 5 total free contacts on one LEDWiz.
If you want each button to be individually controlled then you will need a total of 3 LEDWiz controllers. When you order from GGG you need to order separate USB device numbers so they can be controlled properly. Randy has this already setup on his product pages, but you will need to add each controller to you shopping cart individually.
One thing to keep in mind. USB only supplies 500ma of power. Each LED uses on average of 20ma, RGB LEDs use around 60ma each. The power supplied by the LEDWiz will not be enough. There is a contact on the LEDWiz for external 5v power. You can get this directly off the PC power supply and be OK.
That should be enough to chew on for now.
TTFN

Kaytrim
*After re-reading the information above I made some corrections.