I would like to get around 10 people.
Inital out lay for a 1/10 share (assuming 10) will be around 3 to 5 K depending on aircraft type and what aircraft the group would want. .and assuming 10 people about 120 a month to be able to cover all the maintance, insurance, and hangarage.
Then all you pay is fuel on the aircraft.
That depends on how fast you go. But a realistic figure is around 200 an hour