The reason is that people who buy on overstock or tigerdirect are just buying more bitcoin to replace what they spent. They originally bought the bitcoin as an investment, they are excited to be able to use it for something, but they don't want to exit their position.
I always buy back the same or exceeding the amount I just spent. It's a rule I've always stuck to over the years.
Yes. We gave some away at Christmas and just bought back what we gave. It is nice to end up with the same amount or more Bitcoin at this stage of it's growth for sure!