The Cateye is certainly the cheapest reliable that I know of, but a smartphone != an Edge 305. 305 = Heartrate/Cadence. Smartphone = no heartrate/cadence (without possible additional hardware plugged in). 305 = weatherproof. Smartphone = not weatherproof without some kind of case. 305 = battery life that is adequate for 200 miles in a weekend without a charge. Smartphone = battery life? What battery life?