There is a link to group ownership information on AOPA but I can't remember exactly what it is. I know that the links page
at
http://www.flyfaraway.net/links.html has got it.
I would also emphasize that the "cheap hourly rate" is only achievable if you fly enough hours to compensate for your fixed costs such as aircraft insurance, maintenance, monthly sub etc.
Little niggles can occur with the group that may not have any major niggles, e.g: One person flies the aircraft significantly more then the rest. What do you do if the wear+tear+maintenance costs are increased by this one individual ?
What if you are constantly hassled for aircraft availability by one individual when it is your turn to fly for a whole week but you have not made up your mind which day as yet ?
I am not asking for answers, just stating that you need to be able to resolve subtle matters such as this.