curl --request POST \
  --url https://neo.api.projectdiscovery.io/api/v1/billing/purchase \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "action": "estimate",
  "credits": 1550,
  "payment_method_id": "<string>"
}
'

{
  "action": "estimate",
  "amount_cents": 123,
  "amount_display": "<string>",
  "credits": 123,
  "has_payment_method": true,
  "invoice_id": "<string>",
  "invoice_url": "<string>",
  "payment_methods": [
    {
      "brand": "<string>",
      "exp_month": 123,
      "exp_year": 123,
      "id": "<string>",
      "is_default": true,
      "last4": "<string>"
    }
  ],
  "session_id": "<string>",
  "unit_price": 123,
  "url": "<string>"
}