The buy exists with more than one network and each one has a price and is bought from everywhere, where the truth is I don't know.

An attack to buy all pi coins from the exchanges and transfer them to pi wallets *. The exchanges currently hold 252 million pi coins. Our number is 12 million migrants, and each pioneer must buy at least 21 pi coins from the exchanges... All pi coins will be wiped from the exchanges, making it possible for the Core team to announce GCV 314,159$ already encrypted in the Blockchain...