I've used an Oce Arizona (Fuji Acuity) flat bed in the past and could see one of these machines working for large scale production
A decent second hand machine could be picked up for 20 - 30k (possibly less) but would open up a host of other options
The machine I used, printed an 8ft x 4ft sheet in around 15 minutes at near photographic quality
You could barely feel the ink lay down on these printers
https://m.youtube.com/watch?v=-Sj9lXAFRE8