I like that idea. I'm curious as to the logistics. Does each individual retain ownership of the equipment or does it then become the groups property. I like the concept though, probably one which most groups employ.
I think the real thing to keep in mind here is the difference between a paranormal group, paranormal society, and paranormal agency. Most groups and societies are led like a standard public group, perhaps having by laws, and a mission statement. But not being a commercial entity. The property is shared as you said and there are no real assets of the group as a entity.
Some larger ones have memberships and dues, but usually just to cover operating expenses and the cost of any meetings, rent of meeting halls ,etc. Groups and Associations are generally non-profit and have to show where the dues go.
Alternately a Agency is a commercial entity, which is seldom non-profit. Although in the Paranormal world, many agencies do what they do out of pure love of the field, and make little to no money. As a matter of fact many of the agencies I know end up operating at a loss, but yet are still run as a commercial entity as a business. In these cases the equipment is generally owned by the agency itself, and ownership is divided either as a LLC, Partnership or INC.