cheapest option...yep the free strava app (assuming you have a smart phone).
otherwise something like a garmin 25, then it will upload to garmin, then export to strava (sometimes my stuff arrives in strava before it will appear on my garmin account haha).
Tjere are lots of options for straight strava, to cross platform upload, to stuffing about with uploads, exports then reuploads... just need to make sure you can get it there eventually...
for good info check out DCRainmaker