IIRC in addition to the price of the service, the Minitel was billed by the minute like every phone communication was billed like this. That's why early internet was expensive in France, and it became "free" with DSL connections.

One of the differences between USA/Canada and France/Germany (and perhaps other countries). Local phone calls in Canada/USA are included in monthly phone bill service, whereas in France/Germany, local calls are charged a per minute rate in addition to any monthly phone service cost. I believe local phone-dialup ISPs took off in Canada/USA because of the lower cost.

There was a category of services with the same price as a local phone call. This was one unit every 3 minutes (~10cents) during the day, one every 18 minutes at night. In this price category, I was able to find boards and make friends, talking about Apple II games. There also were free access versions of more expensive sites, provided you knew the X25 address