A watt is a unit of power (energy/time), so saying watt/hr is incorrect. A watt is one joule (energy) per second.Not sure if these numbers are still accurate as they were provided to me by a customer a couple years ago when he tested his PVR. Usage when turned on was 33 Watts per hour. Usage when turned off was 30 watts per hour.
Using your 10 cents per kilowatt you are looking at about 8.640 kilowatts per year so it's about 80 cents more to leave it on every hour of every day for a year.
Someone check my math for me please. 3w/hr = 24 w/day = 720w/mnth = 8640w/yr = 8.640kw/yr
In terms of household power, units of energy are typically given as kilowatt-hours, or in other words 1000 W × 1 hr.
If the thing uses power at a constant 30 W, then it's always 30 W, regardless of how long you observe it. If you are looking at total energy used, then you would say that in one year, you use
(0.030 kW)×(24 hr/day)×(365 day/yr)×(1 yr) = 260 kW-hr (rounding off)
At a rate of, say, 7 cents per kW-hr, then it will cost about $18+tax in electrical energy to have the PVR.