Electricity cost is calculated on wattage used as work (eg. producing heat), not current flow. The same current flows through your light bulbs, but doesn't cost as much since you use less of it as work.
You must use different math than the rest of the world. You should probably refrain from answering questions that involve any type of electronic circuit.
Watts = Amps * Volts... You pay per KiloWattHour, which is 1000 Watts for 1 Hour.
You can't control volts - here in the US, for example, we get roughly 110 or 220 for residential service. Thus, the only thing you can control is current. With volts being non-variable, the only thing you can use to control Watts is Amps (Current), thus, you effectively pay for Amps.
a lightbulb pulling RMS Current of 1 Amp is EXACTLY the same as a Computer Power Supply pulling RMS 1 Amp (assuming it has a high PF) from the electric meter's point of view.
Enigma