Good question --- one that I discovered the answer to a few years ago.
They now price match with Amazon. Yes, you heard that right. If Best Buy has the product, you can pick it up right now for exactly the same price as what you can order it for on Amazon.
But if you think about it, Best Buy is actually cheaper for most people --- because you're not paying the "Prime" tax. The down side is there is no way for Best Buy to match the product variety available on Amazon.