If you look at the reward it makes sense, upgrading from 800 to 1200 is exactly the same thing plus an actual real life physical professional calligraphy of your name in Chinese characters.
$1400 is an in-game wooden plaque hanging from a rope with your name and birth date on, which is bigger and more obvious, so it's more similar to the $1500 reward tier, as such it doesn't include the $800, it includes the $500