I work at a university, so it's a little different, but I think one printer in each department and then at least one in each computer lab would be the best bet.
Most of our printers are MFDs that support color. We have two shares for each of those printers. One has the manufacturer's standard PCL 5c driver. Anyone who needs to print color is given access to this share and the share name ends in "C" to indicate color is allowed. The other share for each printer is the manufacturer's standard PCL 6 driver and we used their driver modification program to block color. We give access to this queue to more people. All access is requested by department heads, but this way we can limit color usage to those who need it and people will give some thought to whether they need something in color or not.
We also set duplex as the printing default. If people know they don't want duplex, they can turn it off. As for allowance, I'm not sure how you guys have your budget separated, but here, each department pays for their own supplies, so they manage their own "allowance" because they know that it costs their department money to print.
