I know that Ballon D'or nomination, and Ballon D'or final shortlist are two of the payments mate, then more than likely your looking at something about Internationals, payments after CL wins, number of appearances and number of goals etc - much like we did in the Rooney sale but even more silly in the amount etc (Basically a Martial version of a huge transfer)
Not arguing that they could afford basically any player in world football mate, but they are not gonna put down 70m or whatever it ends up being in guaranteed payments for Lukaku, he's not a big enough name and frankly not a good enough player for Bayern to suddenly smash their actual transfer record by double.
As i said before, if they REALLY wanted him, they'd be sly arses and get him to stay a year, run his contract into the final one and then try get him cheaper, if we held solidly on the price then they'd convince the player to run his contract out completely.
Same way they did when they tried to buy Lewandowski