€130
If you take your exercise moderately seriously, the Garmin HRM-Pro Plus might be of interest. The heart rate strap tracks pace and distance, with real time data during exercise sessions on heart rate and running dynamics transmitted to your Garmin device. It will provide data such as ground contact time, cadence and stride length, so you can monitor your progress. The latest version of the monitor also tracks data during indoor runs, adding pace and distance even if you can’t get outside.