> Are you saying the software to perform the syncing costs more than a few dollars per month?

The operational costs could be more than that per user if you want regular updates. That's disregarding engineering time.

You need stable business with at least few people employed, to make sure the lights don't go out, and that people fix issues when they come up. Storage cost is probably only small part of the price.

You also don't want it to be VC backed because such businesses will not be worth billions. (and if it will try to become such you will have similar problems as google)