Pylon, thanks for the reply.
If possible, to save time I'd like to avoid making my own Arduino; also, chips like the ATTiny go for about $2.50 - call me cheap 
Maybe there are chips that send TTL, but because the site for the installation is in a museum in Germany, I'd like to err on the side of caution and use something that can handle longer distances, just in case.
I'd read about I2C - seems that was designed more for "on board" lengths, with power being supplied individually at each node?