If you've been wanting to get a new iPhone 6s but have been balking at the price, you may be in luck. This weekend, Best Buy has an insane deal on new phones. But, there's a catch.From now through Sunday, December 20, you can get a 16 GB iPhone 6s for only $1 at Best Buy stores and on its website. While the deal is available to any color model (space gray, silver, gold, or the new rose gold), it only applies to Sprint and Verizon plans, and with a two-year contract. Normally, the phone is $200 on contract, $650 without.The $1 deal also applies to the older iPhone 6 , but if you're going to get a new phone, you might as well buy the newest one, right? The iPhone 6s looks the same as the iPhone 6, but offers a better camera , faster Touch ID, and a pressure-sensitive screen.If you're on the fence about whether to take advantage of the weekend sale, Best Buy's got one more thing you should know about it. If you decide to also trade in your old phone, if it's an iPhone 5 or newer, Best Buy will also give you a $200 gift card. It's basically like getting paid to get a new phone, which is amazing.The only potential negative to this whole situation is if you have to actually visit a Best Buy store. Thank goodness you can just shop online.