I have not made uber huge transfers yet, at least fee-wise, but there is quite something going on in my master league and I only just started my second season.
My most expensive signing was Gourcuff for about 32 million. I guess I am pretty lucky here, telling from what I read. I also tried signing Benzema and Aguero a gazillion times already, but always get rejected.
Else, some notable AI transfers are:
Silva: Valencia --> Milan @64.5
Julio Cesar: Inter --> ManU @55.5
Villa: Valencia --> AS Roma @50.5
Pique: Barca --> Juventus @50
Casillas: Real --> Arsenal @49.5
Also Buffon is now with Barca, but I don't know the transfer fee. I would guess it was at least 50.
Other players who already are with a new team are:
Cazorla, Robinho, Tevez, Zarate, Yaya Toure, Cambiasso, Quaresma, Adebayor, Carragher, Nasri, Bojan, Walcott, Serio Busquets, Maxwell.
Being Chelsea, my biggest competitors in the league so far are ManU and Tottenham. Tottenham bought Diego Capel last season already, and him and Tevez are just absolutely tearing the league to pieces.