The only 'common' item I can think of is brushed DC PM treadmill motors,
however very few are suitable. The percentage of usable motors is small.
You may find something from a commercial conveyor system, possibly similar to a treadmill motor, or a very large servo motor.
Given the cost of everything else in the system (blades, tower, battery, wire, controls, inverter), US$45 shipping from the US is not so bad for something that works well.
G-