RM overpayed for Kaka even at that point, by 2008 Kaka was declining, Milan were right to get rid, Cavani at this stage still has many good years left in the tank. I don't actually believe he is worth that much, but the transfer market is up the left right now, players going for 3 times their true value, 60/70m I believe is what a team would have to pay to get Cavani from Naples Soccer. ADL doesn't have to sell either.
I didn't see your post saying that the agent offered him to PSG, would be interesting if they wanted to leave (Lavezzi will probably be the first gone).
I always said he was overrated, back when people never watched him and heralded him as a great fullback because of a few screamers they saw on youtube. He's a poor man's Kolarov at best.