Earlier quoted context omitted.
They seem really cool. But, I was reading the FAQ, and they claim it costs about $1 to process 80 searches. That seems extremely high. I would have expected that the up-front cost of creating and storing indexes is very expensive, but the cost of user searches to be so low that they're nearly negligible. Okay, it sounds like they lose money with each new added user
I believe they are doing some search aggregation from multiple sources and from what they say they do not seem to be caching results much.
> You must use results you obtain through the Services only in Internet Search Experiences (as defined in the use and display requirements) and must not cache or copy results. (https://www.microsoft.com/en-us/bing/apis/legal)
It's really unfortunate Microsoft doesn't provide a free API that require users to display ads, or at the very least make their ad network accessible to all.