Please keep in mind that both the Target and Best Buy policy explicitly say it has to be available online or locally for them to match it. Sometimes you find a manager that doesn't apply the policy strictly or that doesn't realize it's not available online, and you can get a match. Most of the times they apply the policy correctly and will not lose that much money. In my experience manager can be very open to match if the discount is small. In this case, the discount is 66% and that means that they are selling at a loss. Any good manager will check twice before approving such a price.
At this point, there isn't a Game Stop that still has a Phantom battery available (online or locally), so most managers will refuse to match
Still, with perseverance and a bit of luck, a discounted battery can be found...