curl --request POST \
  --url https://api.hubapi.com/marketing/v3/campaigns/{campaignGuid}/budget \
  --header 'Content-Type: application/json' \
  --header 'private-app: <api-key>' \
  --data '{
  "amount": 123,
  "name": "<string>",
  "description": "<string>",
  "order": 123
}'

{
  "createdAt": 123,
  "amount": 123,
  "name": "<string>",
  "description": "<string>",
  "id": "<string>",
  "order": 123,
  "updatedAt": 123
}