From the type of questions you are asking I would suggest you get down to a couple of local airstrips and talk to the owners. You'll get some decent information which relates to your local area. It is very difficult to do this from the net as there are so many gottchas dependng where you are based.
The costs above are potentially coreect - but your local situation will vary.
To be blunt hours building is not that popular with clubs or groups. The group I was in threw out 2 hours builders - they simply were not looking after the plane whilst they racked up the hours and maintenance costs.
Leasing is a possibility but as has already been mentioned they want to see a reasonable return on their capital and that means hours flown. So 40 hours a month barely does that.
Some in your position have bought cheap permit aricraft and sold them on when they got the hours they needed. With a good purchase this makes a lot of sense - but you need to know what you're buying, how to run your own aircraft and have the money tied up for a period. This is probably the cheapest method - but you need to know what you're doing. From your posts I'm guessing that would mean help from someone who has been through this sort of process. Believe me owning an aircraft is a great way of emptying your wallet!
My advice would be to set up a deal with a local flying club - it avoids all the things which you don't know about and all those associated risks. In the short and medium term it will probably be the cheaper and certainly the easier option.