{
  "method": "buy",
  "body": {
    "item_id": "aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaaaa",
    "max_price": 12.5,
    "custom_id": "documentation-order-42",
    "target_trade_url": "https://steamcommunity.com/tradeoffer/new/?partner=12345&token=TESTONLY"
  }
}