You don't pay for GPS data. You can turn data off on your phone when you ride.
I don't use sensors on my bike. I just let the phone use GPS. It's a little less accurate, especially as I ride. I think after I upload the ride, it gets recalculated better. I could add a speed sensor, but I just don't bother.
I use
ridewithgps. There are other apps, and I think
Strava is the most popular.