An open source smartwatch.
A basic Casio is $13.50 – can you really buy a smartwatch for the price of two of them?
tl;dr: yes. And bloomin’ impressive it is too… More here.
Hard to argue with the cost, the sheer geekiness of the product and the potential. Design, however, is too important in a watch for me so this would not work. The potential, as I said, is strong though.