We have to pay more than Napoli because we are a significantly richer club, not because of negotiation skills, and even Napoli paid a fortune for Higuain. Tevez, Vidal, Barzagli, Lichtsteiner etc all arrived at very reasonable prices, indicating that we aren't notorious overpayers.
This isn't a street bazaar where you haggle over a few euros up and down. If the selling club has no reason to sell, they don't have to. If there is conpetition for a player, price inevitably goes up.
Name me one club with a great negotiator whobregularly find bargains. Most football fans in general would probably answer Juventus.