what is a fair price per hour or per month for a public privite aircraft school?

Answer 1

Well the most important thing is where do you plan on going to school. One of the cheapest places is in the USA.

Here is one site that breaks down costs.
http://www.sportplanes.com/training.htm

They are quoting $47.00 per hour wet (fuel included) for a Cessna 172 / 152

And $25.00 an hour for an instructor

Average flight time from start to stop you can guess about 70 hours. Plus classroom time, and tests.

Most one stop flight school should be able to help you get your PPSEL (Private Pilot Single Engine Land) VFR (Visual Flight Rules) license for around $4000-$5000.
The more fulltime you goto school the faster and cheaper it is.

Good luck

Answer 2

Can you tell us in which region of the world ? There is a large difference between Western Europe, the USA, South Africa etc....

It also depends a lot on your aircraft type choice.
If you go for state of the art modern new fleet of SR20's and go right away for 21st century glass cockoit training with flight sims and all, it will be more expensive than if you choose to fly vintage C152 or even bette PA18.
Both are fun and interesting approaches, but quite different.