When I managed a LQS which is a nonprofit I asked for the store to invest in a longarm machine. Since the nonprofit runs mostly on volunteer there were problems. These are the problems that came up at the store. Too many hands at the machine tends to bring thread tension issues because everyone is messing with the tension. So the solution to this was only 2 or 3 trained persons were to run/use the machine. They would quilt for the store samples and also for customers, every 4th quilt could be for them selves or they could get a percentage of the sale.
As word got around the machine was producing a good amount of work which kept the machine worthwhile. Since I left I have heard the now they only have 2 persons that volunteer and their work is still in the learning stage.
All this to say that as long as you have someone willing to be trained and to practice, practice, practice it would be profitable for the group to get a start up 12-18" machine set up.
Some of my queen size quilts takes me 4 to 6 hours is all runs well....and then there are what has been mentioned and then they bring the batting in a bag and you have to measure and maybe even cut, the back is pieced and the ends are not even so you have to trim it, and oh so many more that the list would go on and on. enough said,