An 8051 controller, receiving RS422 as originally proposed, would be a big help in controlling transmission errors. Your local micro can be 20-pins (or smaller), driving a pair of Allegro UCN5833A chips. Your big expense will be labor, especially the wiring. Reduce the labor of wiring by fanning out common 40-pin IDC cables normally used for IDE hard disk drives. Rather than trying to buss the power, use a seperate power and driver (pair) for each lamp so you can just send an adjacent pair to any given lamp. Anything to get them prewired off site.

Local power is also a good idea. You can buy small open frame switchers from various surplus suppliers, such as http://www.allelectronics.com CAT# PS-2133, or http://www.goldmine-elec.com cat #G14598. I don't know if thes particular guys ship to where you are, but you may also have local suppliers.

Short circuit protection is probably going to be important; with 3000 lamps you'll have some shorts here and there (unless you do all of your own wiring). A low value resistor in the PWRGND line of each driver chip to be monitored for overcurrent would solve this, cheaply. (0.22 ohms, LM339, threshhold 150 mV, approx. 0.68A per 32 channels).

Be sure that the builders are aware that they need to ventilate 648 watts of heat. They proably aren't expecting this!