I agree. There's not enough time left in his career for his to be largely associated with us. The sensible thing to do is spend that money improving our squad and making the whole greater than the sum of it's parts.I just think that when you're looking at paying £170m or whatever figures are being quoted, you'd want a player with his best years still ahead of him rather than behind him. In fact i'd want three players with their best years still ahead of them for that money. As for shirt sales, whilst i'm sure they'd recoup some money, nobody really knows how much. His shirt sales as a barcelona player won't translate to the same numbers as a city player.
On the other hand though in order to catch the next Messi on his rise you have to gamble fortunes (3 or 4 potentials would be in the same ballpark).
So if we want a true superstar then maybe this is our only option. (Today I'd prefer to be sensible. If he signs then I'll be over the moon. Giddyiness always trumps!!!)