This was a questions asked of me recently by one of my customers having receieved a large electricity bill since his projector was installed. CRT projectors draw typically about 2 amps when running. Quite a bit more on startup when the EHT and big capacitors charge up. Looking at the common projectors about 300 to 600 watts. So lets say it is 450 watts. Electricity is charged by the killowatthour kWh this is the standard unit we receive our Electric bills in. Looking at my bill (supplied by a Gas company ) A kWh is charged at 6pence. So to run his projector for one hour would use. 0.45 of a kWh which would cost. 0.45 x 6 = 2.7 pence Perhaps some one could do the figures for the DVD player, scaller, amp etc. But pretty good value for money I'd say.