I actually tried pricematching twice at Best Buy. First time I was shut down because I got stuck with a new employee that had a manager by her side, and he said they don't pricematch online stores. Of course he said this after he saw the price difference of 69.99 to 29.99.
Then a couple of days after that, I stopped by a different Best Buy on my way home from a mall. I picked the employee this time that I thought would be the least strict, (girl around my age), and sure enough she did the pricematch. I just handed her a game and the kit then gave her the printout and told her about the lower price on the kit. We engaged in small talk while she was ringing everything up and changing the price of the kit in the system. She did ask me about the store, but she didn't seem to care that it was an online place. I find it better to be polite than forceful when dealing with employees. Plus I always try to be polite with the ladies.
Whenever I price match huge differences (online or ads), I just normally try to get the employee that will be the least strict. Best Buy categorizes their customers, I like to categorize their cashiers.