Speaking of jumping in late!
Anyway, if you’re not looking for perfect sync and just want to trigger 9 cheap DVD players to play simultaneously you could easily go with those Powermid cheap IR/RF extenders.
Markertek sells them – the funny triangular thingies. They actually work pretty well.
The transmitter takes an IR input, encodes it to an RF signal – sends that to one or more receivers, which reencode it to the original IR signal at or near the controllable device. (DVD player)
You get a transmitter/receiver pair for under 70 bucks and extra receivers for under $50.
The RF is omnidirectional and is pretty good room to room, so typical stick-built walls aren’t a big problem
The whole rig for 9 IR send/receive stations should run you under $500 and would probably fit in a Pelican 1650.
Plus you’d control all 9 devices from a single DVD remote control, so you’d get all the remote’s capabilities – power up and down, jump chapters, etc.
Not pretty, not really very “high tech” but pretty cheap and I bet it would work just fine for the kind of portable temporary installation it sounds like you’re planning.
FWIW, YMMV.
FCP since NAB 1999
creator: muti-track movies
http://www.starteditingnow.com