Is search arbitrage legal?
Yes. Buying advertising to bring visitors to a page that shows search ads is legal in the countries where it is commonly practised, and it runs under written contracts with search engines or their partners. What can be illegal is how it is done: deceptive adverts, hidden ad disclosure, privacy breaches, or fake clicks, which is fraud.
The model itself is ordinary media trading. The legal exposure comes from consumer and privacy law. In the United States the FTC Act prohibits deceptive advertising, and native ad disclosure guidance expects paid content to be recognisable as advertising. In Europe and the UK, GDPR and cookie rules require consent management before most tracking.
Separately, contract terms matter as much as statute. Breaking AFS program policies is not a crime, but it ends the business. Generating invalid clicks deliberately is a different matter: Click fraud has been prosecuted as wire fraud and computer misuse. This is general information, not legal advice for your situation.