What's cost of sending a ship to Mars? If $x, can a group provide another $x so in effect we can send 2 ships. Spread the risk and/or send double the supplies a

What's cost of sending a ship to Mars? If $x, can a group provide another $x so in effect we can send 2 ships. Spread the risk and/or send double the supplies at the same time knowing that we get window of launch opportunity only every 24 months