Everybody is responsible for their own mics, cables, DIs, stands, etc. Then it's best if one guy owns and stores the PA and speakers (+stands&cables). The owner gets paid an equal bit from each member (including the PA owner) for use of the equipment). That's the easiest and fairest way to handle it, I've found.

Each of the members, if they are professional, should be expected to own quality gear and be responsible for keeping it in good working order. Also, be prepared to pitch in and lend a hand for set-up and tear-down. The owner of the system calls the shots for packing up and transport.