How about sinking your money into a new aircraft and leasing the aircraft to a flying club, this would allow you enter the business with much less risk than most options. You can get started straight away, while collecting the costs for your idea to branch out as an indepenent school. You will have an aircraft that you will own a greater precentage of, and being newish will be an asset to your school.
Diamond Aircraft have a set of spreadsheets for a lease-back arrangement on their DiamondStar DA40TDI aircraft at
http://www.diamondair.co.uk/starter2.html
These spreadsheets give you some idea of the costs involved in runnning the aircraft. The interest rate they use can possibly be bettered as well.