It is a simple, while likely not most optimal cost effective way to compete with Google :)
There is Bing doing this already...
Is there a need for "domain specific search"?
Building an Azure Search Engine with Anthony Brown @ NET Rocks! vNext
bruinbrown (Anthony Brown) · GitHub
Azure Search – Managed, elastic, cloud search service for developers | Microsoft Azure.
Azure Search Documentation | Microsoft Docs
azure costs - azure cloud cost optimization made easy
DuckDuckGo - Wikipedia
"DuckDuckGo is now advertising-supported but the user has the option to disable ads.
The search engine is written in Perl" (!?)