Not sure what you classify as expensive. I have this Proteus unit: https://www.fitnesszone.com/product/PROTEUS.html https://www.fitnesszone.com/product/PROTEUS.

Not sure what you classify as expensive. I have this Proteus unit: https://www.fitnesszone.com/product/PROTEUS.html https://www.fitnesszone.com/product/PROTEUS.html ~$1,500, and it calculates via the flywheel, not seat movement. Not sure how much distance I have on it, it doesn't hold stats after a power reset. I'd guess around 1M meters after several years, but I usually only get to use it about once a week on average. Rowing is usually Tuesdays on my M-F workout circuit.