my teammates and I need to develop some device on one of our collage courses. One of it's features is to be able to determine it's position relative to it's start position. Distances could be up to 1 kilometer and it shouldn't miss more then 10 centimeters. Most important thing about this is the price - it should be as small as possible. GPS is too expensive. We thought of placing three sticks somewhere in area and then to transmit radiowave or ultrasound from our device to them and to measure distance that way, but we don't know how much would this cost. Does anyone have some better idea or at least knows how expensive would be our idea? We're new in this area so I appologize if this question seems stupid to someone.
Thanks in advance.