IMO you can look for this in two ways. You can buy the cheapest engine and adapt it to a propeller designed airplane. The adquisition cost
will be very low, but the cost per flight could vary from inifinite (total expended/number of flights) to about $300 (if you can squeeze from it 5 flights)

Or, buy a decent engine, a proven and reliable design etc, and spend about $5000. Unless you are very unfortunate you will easily extract from it 500 flights (it could be much more) and spend about $10 per flight , excluding fuel costs. Not to mention the pleasure of having a
excelent performing aircraft with a turbine that works anytime you want.


Enrique