I think $10 is too low an estimate.
replyAn AirFanta 3Pro on low (2) is 5W, which is $10 on average (but more like $15 in high $/kWh places like MA and CA).
replySome people are paying north of 0.50€/kWh (after tax), so this amounts to 22€ annually.
replyThe point stands. If you care about this, it's a personal choice whether that comfort is worth ~20€. I would wager many people say it is.