Radamel Falcao from Athletico Madrid to Monaco (2013) - $79.2 Milllion
Though in the end, it all amounted to nothing, the rumor mills were in full swing regarding this Columbian striker before he ever even kicked a ball for his new club.
The subject of another bidding war between the ultra-rich, Falcao ultimately ended up at newly minted AS Monaco, and that's where the trouble really started. First came the rumors (since disproven) that his birth certificate had been falsified and that he was in fact two years older than he claimed. Strikers peak around 27 and are generally considered on their way down by 32 before retiring around 35. In that window, two years make a world of difference.
After that came the rumors that Monaco's wealth was just a house of cards and that the implementation of tax policies would force them to sell their prize asset before he even started a game. Fortunately for Monaco fans, the troubles seem to have passed...now it just remains to be seen if Falcao can deliver on the field.