Many would be ~ five cents/month. AT&T new IoT pricing can deliver 3 megabytes to 300 devices for 8 cents/month each. This price is an order of magnitude cheaper than any telco IoT offering I know and beats most prices of LP WAN. Many IoT devices require very little data. Your blood pressure monitor or scale is likely to upload a few times a day or fewer. Your smart electric meter does not need to be sending continuously for most purposes. Turning on your air conditioner or coffee maker when you're headed home requires only a few bits. Your baby monitor camera or Pandora in your car may require more, but there soon will be billions of devices that don't need to say very much.
Most telcos are looking for a dollar or more for each connected device. I think that will drive people to Wi-Fi instead, especially because the Wi-Fi chip is much cheaper than LTE chips. Telcos have high expectation for IoT, but nearly all is going Wi-Fi today.
AT&T is charging in with extraordinary pricing for projects that will have 50-1,000 nodes. $25 buys you 1 gigabyte, delivered to hundreds of locations, $60 covers 3 gigabytes,