Do you honestly think no one tried to sign those Juventus players when they went down? And what did Buffon go for? £20m? I still dont think it was close to the world record fee.
You also have to face the fact that De Gea might himself want to move back home. In that case, you cant really demand a huge fee since his destinations are limited. GK's are valuable but doesnt mean they are going to go for £50-60m. That is just crazy. No GK will go for that value.
Yes, Buffon moved from Parma to Juve at 23 for a world record fee for a goalkeeper, and that is extremely young. Same with De Gea, he moved at 20 for £19 million. And both were moving from relatively small clubs to big clubs. Goalkeepers with this level of talent are
extremely expensive, even when they are still young and raw.
I also think all this 'going back home' nonsense is stupidly overstated. There aren't many footballers who are getting homesick and moving back to their country because they miss their mum or something: Fabregas - moved because Arsenal are shit and Barca are a great team; Balloteli never settled at City because he's a nutjob and there were better players. Two examples, and I can't even think of one single player who left a big English club to move back to their country because 'they wanted to go home'. It's retarded to even think footballers are that stupid.
The only examples of a world class goalkeeper moving from a big club I can think of are Van De Sar and Julio Cesar (if you consider him to be world class) - the former was dislodged by an even better player (Buffon) and the latter had suffered thanks to injuries.
To bring the point home; imagine a club like Barca coming in and trying to negotiate for the purchase of Lloris from Tottenham - they would get absolutely bled dry before they signed him. And Spurs aren't exactly the level of club I'm talking about here.