Of all the gadgets you've bought, which one was the most waste of money?
For me, I was one of the lucky few who was invited to purchase a Google Glass. It was an amazing experience for me (before my move to silicon valley), going to the NYC google offices to pick it up in person above Chelsea Market. Did I use it after that day? Maybe twice.
I remember about 2 weeks after I purchased it I was wearing it around Manhattan on a very cold day. It had to have been below freezing outside. It's never held a charge since.