Some have said that Marchisio's transfer value is 25-30m.
Vucinic is around 15m (according to some sources)
Matri & Quags are probably worth less than 10m each. Giovinco worth similar to Matri & Quags.
Marchisio sale is easy as he is in demand and get you 25-30m straight away. Higuain and Jovetic are going to cost us anywhere between 45-60m depending on final negotiated prices.
I think Marotta first needs to focus on selling players. If someone wants to pay 15m for Vucinic, take it. I would also sell BOTH Matri & Quags.
If Marotta can sell Melo, Matri, Quags, and Vucinic - you should be able to get anywhere between 35-40m for those - bringing the net spend to ~20m. Melo was not part of the squad and you lose 3 forwards (4 if you include Bendtner who will be gone). Llorente, Higuain, Jovetic and Giovinco would be the 4 forwards (2 support strikers and 2 center forwards). Bring in one of Gabbiadini, Boakye or Beltrame as your 5th forward.
Under the Lippi/Capello days, Juve squad only had 4 strikers + 1 primavera or youngster. But the strikers were quality (Trez, Ibra, Del Piero, Mutu for instance).
If I really went nuts I would sell Giovinco as well and have a complete overhaul and have 4 strikers: Jovetic, Tevez, Higuain, Llorente = IN 60-70m. Giovinco, Vucinic, Matri, Quags, Melo = 50m.
Hard to do though.