Now buffon is the player who has the biggest transfer value in juve. He can fetch us a gud sum which can be used to tighten the defence with 3 or 4 players and sum creative midfielder.

I used to be one of those who thought zidane's move to madrid was a brillinat move even though he's almost irreplaceable. But we sold the guy for a record fee and bought 3 great players in Buffon, thuram and nedved.
But i have my doubts about our current management, we never really lacked the $$ and thats a mistake people keep repeating over and over on this forum IMO. Since our return to serie A last season the management spent almost 100 mil euros on buying new players (not counting the players we've got for free).
Our real problem is not lacking the funds or the money to spend, its really the poor management of those funds and speding them on the wrong players. Even one of the major share holders in the club (don't remember he's name right now) said that those on charge of the club have wasted the funds that they've got on mediocre players that did not gave us that extra edge over other teams (with the exceptions of few "amauri and sissoko" probably).
Selling Buffon right now would be a huge mistake, cause we need to add more quality to the team. But selling those few great players that are left in the team to sign yet again avarege players wouldn't be a smart move ......