How can one justify the cost of an LED lamp compared to a traditional light source?

The cost of the LED lamp is just one factor. It is necessary to also compare the operation cost (electrical cost) and maintenance costs savings if possible. Light sources consume watts over a period of time. Assume you operated 1 watt for 1,000 hours. You have then consumed 1,000 watt hours or 1 KWH (kilowatt hour). On average, the cost per KWH in the US is about $.12/KWH. So, 1 KWH would cost you $.12. Therefore a 60-watt incandescent lamp operated for 1,000 hours would consume 60,000 watt hours or 60KWH at a rate of $.12 per KWH and would cost $7.20 just to operate the lamp. If you replaced that with a 12watt LED Lamp, it would consume only 12,000 watt hours or 12KWH @ $.12/KWH or a total cost of $1.44 to operate.

This is a savings of $5.76. Keep in mind that the LED may have a life rating of 25,000 hours vs only 1,000 hours for the incandescent lamp. This means that the savings in electricity over a period of 25,000 hours totals $144.00 for the LED Lamp. This already justifies the cost of the LED Lamp.

Also, realize that you are replacing that 60-watt incandescent lamp 25 times during the rated life of just “one” LED Lamp. If you multiply the cost of a 60 watt household incandescent bulb by 25, you will notice that you are spending almost as much for 25 bulbs vs. just one LED bulb. If replacing bulbs less often saves you on maintenance costs, there are further savings. It just makes sense to switch to LED's.

Also note that Utility rates vary considerably compared to the average US rate of $.12/KWH. Rates can be as high as $.20/KWH. Review your Utility bill and divide your monthly amount billed by your monthly KWH usage. You will then see your average KWH rate.