Or, even better, the printer exposes toner levels and page count -- it's a printer, what else is there to know? -- via SNMP so you can, say, put it in Observium

Or, even better, the printer exposes toner levels and page count -- it's a printer, what else is there to know? -- via SNMP so you can, say, put it in Observium and get nice graphs with minimal effort.