How much would it cost to back pack across the world?

How much money do you think one would need in "travel account" before they could back pack across the world, minus they shady parts of the middle east? I mean nothing fancy for accommodations, trying to stay mainly at hostiles and hopefully monasteries in asia if I am luck. With very minimal "extra spending". To be honest I'm thinking ten grand. But I have no clue, I want to travel,find the world and myself.