curl --request POST \
  --url https://api.sonderplan.com/v2/billable-item \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "id": 92834,
  "name": "Aspera Upload",
  "description": "Upload to Aspera (per TB)",
  "unit_name": "Terabyte",
  "buy_cost": "10.00",
  "sell_cost": "20.00",
  "taxes": [
    {
      "id": 3247,
      "name": "GST",
      "rate": "10.00",
      "total": "151.00"
    }
  ],
  "custom_fields": [
    {
      "id": 7823,
      "name": "Type",
      "value": "Video Editing",
      "value_id": 8973,
      "update_key": "2_1_7823"
    }
  ],
  "currency": "AUD"
}'

{
  "success": {
    "id": 1
  }
}