Here's what I see when I get the promo
If the img tag doesnt work, just go here:http://postimg.org/image/lmkwns8vv/http://postimg.org/image/rh51gr5yt/
Unfortunately, I found out it's targeted. I tried with my wife's amazon account using the link that I clicked to get to that page, and her account only showed the 6/12/18 month financing options.
My amazon spend ranges around 1500+ a year, which probably isn't that much, but I would say that I spent over 3k last year on some big purchases. It's possible this raised some flag at Amazon to allow me this promotion.
You could always try refreshing the cart page where it typically promotes the Chase Amazon rewards card. I had to refresh the page several times to get this promo to show up. Good luck