Looks like the "cost of mining a coin" is a LOT less than "$1000 - $2000".
No i stand by my numbers and your calculation did not deal with miners who did not win a coin
One factor that may help limit the increasing energy consumption is that if the price of bitcoin should drop drastically mining might become a losing proposition. Currently, at the average cost of $0.12 for electricity in the U.S, it costs $1,567.88 to mine one bitcoin. And at the lower cost of $0.04 available in some locations, the price to mine is just $522.62
See
http://www.digitaljournal.com/tech-and-science/technology/op-ed-bitcoin-mining-consuming-more-and-more-power/article/509257You will also find calculations for the estimated cost of each transaction using google (fixed search results)