Not shop lights, but I swapped the 60 watt incandescent bulbs throughout the house with 60 watt equivalent LED bulbs that I bought for $.99 each at Lowe's on Black Friday and noticed about a $30-40 drop on my electric bills each month. So replacing the 38 or so bulbs in the house paid for itself in about a month and a half.
They are brighter by far than the standard bulbs and the instant turn on is nice too!
Three of them have burned out but the rest are still going strong. I bought a few extra so I am good so far, hopefully they will last a year or more, but either way at that cheap price they more than paid for themselves! I plan to buy more this year if they are on sale again. I also need to buy the LED replacement bulbs for our ceiling fans to complete our conversion to LED.