How can I get money at arrival?
You can always cash some money at an ATM with a credit card (e.g. Visa, Mastercard ...) at the airport. A bank card (e.g. Maestro) will work but not in all banks. Some banks gives you just 300.000 COP but mostly you can cash a second time the same amount. Bancolombia provides 600.000. If possible, don't cash at an non guarded ATM to prevent skimming. Preferably, use mall ATM's or ones located at crowded principal streets. And check your account whether all transactions are okay.
Here you can read more about this subject.