Electronics are the most expensive part by far for something like my RC project XFire. Like most, I am on a tight budget. I only want to build something if it is fun (fast and tough). But it also needs to be cheap. With all electronics the cost is usually related to the power that the electronics need to handle. P=IV so we need to consider both the current and the voltage. Like any product, availability is also a huge factor in cost. If China is making a million size x motors and less of size y then size y motors will probably not be the best value. Sometimes the availability will determine the cost more than the actual cost to manufacture the component.
Motors and kV (RPM/V)
In order to use a variable speed electric motor you need something that can moderate the voltage going to the motor. Continue reading