Ta for the info on the brightness - sounds good.

As for the displays themselves, I know they're not particularly cheap, but some of them are fairly simple to support - they have the video memory on board, and are simply accessed via an 8-bit bus. See for example http://202.241.158.226/english/cl/index.htm. I'd guess this is what the empeg uses, but can I find a source for these things in the UK (or anywhere)?