You can use Remix connected to the testnet to get an estimation cost of each function call. The following table presents the cost of the main methods defined in the auction contract according to Remix:

A basic transaction (simple transfer of ETH) has a minimum gas requirement of 21,000 gas. Consequently, if you are just transferring funds and not interacting with a contract, your transaction takes 21,000 gas. If you are interacting with a contract, your transaction takes 21,000 gas, plus any gas associated with the executed method.