This buying function in the tutorial never pays the contract, does it?

Question

It doesn't look like the contract is ever paid here. Is this a miscode or am I reading it incorrectly? Where does the exchange of ether occur?

function buy() payable returns (uint amount){
    amount = msg.value / buyPrice;            // calculates the amount of token
    if (balanceOf[this] < amount) throw;      // checks if it has enough token to sell
    balanceOf[msg.sender] += amount;          // adds the amount of token to buyer's balance
    balanceOf[this] -= amount;                // subtracts the amount of token from seller's balance
    Transfer(this, msg.sender, amount);       // execute an event reflecting the change
    return amount;                            // ends function and returns
}

Answer 1

this buy function transfers to the buyer an amount of tokens against the received ethers. It gets payed because this function is payable so it receives ethers via msg.value and allocate to the buyer an equivalent amount of these tokens in balanceof[].