This question is a little open.
To use a Z3C you need the physical device and a Meraki licence. The licence is 1, 3, 5, .. years long. You might buy the appliance outright, lease it for a monthly cost, or get it from an MSP for a monthly cost. If you buy or lease it then you will also be buying a licence.
The monthly cost of that component is the cost divide by the number of months in the licence.
Now you have the operating costs of whomever you get the Internet from. You might use a cellular data plan. You might use fixed-line broadband service.