Stekelenberg cost 7m because he was on the last year of his contract and plus Ajax are notoriously cheap sellers. Do your research...
He may not cost 15m but he sure as hell would cost more than 3-5m as you stated considering he i Brazil's No.2, heir to Cesar, and a key part of Santos (who do NOT sell players for cheap)
De Gea cost 20m
Neuer cost 18m (was on the last year of his contract)
Where exactly are they cheap?
De Gea- Europa Cup winner and very young, Neuer German #1.
The top transfer costs for keepers-
Buffon-54.2
Neuer-22
De Gea-21
Peruzzi-17.8
Muslera-11.75
Craig Gordon-10.2
Courtois-8.8
Barthez-8.8
Roberto Jiménez Gago-8.6
when Sirigu moved to PSG it was for only 3.5 despite being young and an Italian NT member, Viviano was around 8 after his co-ownership was resolved. Van der sar moved to Fullman for around 8 and to ManU for around 3.
here is one rumor-
After having observed him for a long time, AC Milan are weighing up the chance to submit Santos an offer for purchasing Brazilian international goalkeeper Rafael Cabral Barbosa (21), currently on a deal with Peixe until August 2014. His ownership is currently esteemed around 2 million euros, but Brazilian club are willing to wait for his debut with Seleção, in order to increase their request.
and as for saying he is the Brazilian #2, the game against the US was his first game for Brazil, Jefferson, Victor, Diego Alves have played more games for Brazil as Cesar's backups, and Neto has been called up multiple times too (although he is waiting for his first cap)
Rafael is good but hasnt shown anything in Europe, so I highly doubt he will end up being as expensive as you think.
If Binho goes to Santos we should be able to work him in as part of the deal, and hell, we could loan them Gabriel too