I also don't think it's a good idea having some people who are in for 30K, and some who are in for 10k. Each will have different priorities, and have different attitudes towards the aircraft, because it has cost them vastly different sums.
I'd also suggest that if people are struggling to buy into the group, then perhaps they aren't the best people to have in the group. No offence intended, but I imagine with a serious aircraft such as a new SR22, there will be serious bills at certain stages, and you really don't want people in the group who can't afford them.
dp