Sorry no matter how expensive your electricity is, you are paying $980 for 700Kh of LTC mining when you can get that for half the price in a GPU.
At 500 watts for a single GPU giving you 700Kh you would pay $54 a year (at $0.15 Kwh) to run it.
The breakeven on the electricity would require you to mine for 7-9 years before these devices recovered their excessive cost.
For easy math, a GPU of about 700Kh mining costs $500 (for round numbers) so for these to be competitive they have to cost $50 USD
When they hit that price (or close to it) you should buy all you can get. There is a small window then Alpha T starts selling their units.
Just my 0.02BTC
your math wrong.
0.5kw * 365 days *24 hours * 0.15Kwh = $657
But 7970's power consumption is 280w, not 500
So
0.28 * 365 days * 24hours * 0.15Kwh = $367,92 - electricity cost per year
280 Watts.
Let's convert this number to kiloWatts by dividing by 1000, to get 0.28 kiloWatts.
These devices, that have been on for 24 hours, have consumed
0.28 Watts × 24 hours = 6.72 kWh (kiloWatt-hour) of energy.
Finally, since energy costs you $0.15/kiloWatt-hour, these devices have costed you:
6.72 kWh × $0.15f/kWh = $1.01 a day * 365 days = $368.65 to run a GPU for a year
Which gives you 700Kh?
Now instead you buy 10 of the USBs and run them LTC only and you have spent $980
Let's say they use 20 watts a day ($0.07 a day) or $25 a year to run
$980 + 25 = $1005 for 700Kh is total operating for a year for these.
A GPU of the 7970 type is $440 plus the $368 for electricity is $808 cost to operate for a year.
Both the GPU and the USB Dual miners require a computer so we wont add those in and we wont add in the $80 for a good USB hub to run 10 of them.