You are comparing transfers with players who still have alot of time on their contracts left, Javi Martinez still has 4 years left on his contract and Oscar was only 2 years into a contract at Internacional. Neymar on the other hand will have 1 year left on his contract in 2013 when it is reported Barca will sign him which will cut his price massively.
Taking into account how long he has left on his contract the talks of 60 million and 50 million are absurd, If Santos demand this sort of fee then I don't see him moving until 2014 when he will be on a free.
I do hope Barca sign him as he is so young and I have no doubts about him succeeding in Europe ,he would be an investment for both the present and the future.