So I can get BfA for 49.99, or the complete edition plus 30 days game time for 59.99. I have everything up to legion but haven't played in a while. Does the complete edition have to be on a new account only or will it simply add Azeroth plus the game time to my existing content? Reason I ask is because it's cheaper to get the complete edition even if you have the other stuff, UNLESS, the expansion comes with game time but it just doesn't specify.

The only expansion that comes with time is the battle chest pack on a fresh account. As you already stated, to add 30 days it’s an extra $10 if you purchase BfA upgrade to your current account.

Damn. I figured that was far too simple of an oversight to actually work in my favor. Sad day