How is the exchange rate for Bitcoin established?
I notice that bitcoins are sold on the market with alternate prices.
How is their price established ?
Who is establishing how much a coin worths ?
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
There is no central pricing body. The open market is determining the price. What customers of the exchanges are willing to pay and the price at which sellers are willing to sell is the price of bitcoins.