LoadUp Gifts via Rakuten offers an $50 Xbox Gift Card for $50. Apply coupon code "SAVE20" to cut it to $40. (You must sign in to your Rakuten account to use the code; the gift card will arrive via email.) That's tied with our mention from two weeks ago as the best deal we've seen. (It's the lowest price today by $10.) Deal ends December 27.
You very likely are putting your laptop battery into an early grave.