Its pretty simple
1. Unplug all cables from cabinate.
2. Wrap cabinate with a plastic.
3. Use thermocol to cover cabinate from all side
4. Seal it with a salo tape
5. Use plastic bubble to cover from outer side to provide additional protection.
6. Place it in a carton
There are several courier companies like UPS, USPS, DHL, FedEx and many other whose courier charges are much cheaper.