I used the same calculator. 40 hours a week comes out to 5.7 hours per day, I put in the national average of $.11 per kilowatt hour. Your cost calculator said that the cost to run a 100 watt light bulb for a year was $20. If you had your 100 watt light bulb running 24 hours a day for a year... the cost would still be only $96.36. What figures did you input?
I am a big fan of LED flash lights, but I don't think that they make good sense yet for interior lighting. But if Comrade Obama gets his way and out rates "necessarily skyrocket" they may pencil out better in the future.
Revised with an 8 hour "day"...it takes $25.40 per year for the 100 watt standard and $3.05 for the 12 watt LED...so we are looking at maybe 2 years rather than 6 months to get your investment back if the LED is around 45 bucks.