I would be looking to joint purchase with 5 or 6 friends, some with licenses and a couple who would like a license. I was then considering perhaps allowing a few more people who can join the group in a similar way to the group i was in basically just charging a small joining fee + a competitive hr rate.
Well, if you do JUST the first bit you save some money because you do not have to maintain the aircraft to PT standards, when you have high utilisation it does not make a lot of difference, but IIRC (sure someone who is more up to date than me with the requirements will let you know), on PT standards you need the 50 hr check doing on date even if you have not flown, whearas otherwise you can leave it until you get that utilisation. Important in the winter especially, can make it not worth hiring it out to non share owners.
Also, you will STILL need to have some sort of system in place for those of you that ARE part owners to ensure monthly bills are still paid even if no one hires it (tech aircraft, dud wx etc.) this will probably end up initially much like the groups monthly payments you have talked about that you do not seem to like, though hopefully over time you would build up a surplus for these periods.