Just to echo and amplify Steve's comments, you will in fact spend a bit more to power your plasma than an LCD and you will spend a tiny bit more dealing with the fact that the room will be a tiny bit hotter, but the numbers are nowhere near $10 per month.
We can actually do a quick "back of the envelope" calculation. If you assume the plasma will run 200 watts above the LCD (a pretty reasonable guess in the larger sizes), you will use 1 additional kilowatt hour per day of electricity (assuming 5 hours of viewing). That's 30 kw/hour per month or about $2.50-4 depending on where in the country you are. The incremental cooling is really hard to measure, but over the entirety of your house, the plasma is like running the equivalent of 3 more 60 watt light bulbs worth of heat. I cannot believe the cost of cooling that is more than $1-2 per month and it's partly offset by the countervailing heat in the winter. Let's just call this $1 per month on average.
If we take those together, we're at $5 per month in markets with pricey electricity (like California) although if one were buying "Tier 3" power in California you could even end up close to $10 per month. In Nevada, however, power runs around 11 cents kw/hour and this would get you below $4 per month all in.
There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working.