This is new. I bought it as a spare for my large weed eater, and has been sitting on my bench for 6 months, never used it
My weed eater seized up so this is of no use to me anymore
The list price for the Heavy duty 5.0AH is $149.99, I bought it from Amazon for $99.99
I could only find an Amazon ad for a 2.5 AH battery, List price $119,99, sale price $79.99 as shown
So the $50 is very reasonable