The details of DDG's arrangement with Bing are obviously not public. However, it is a very safe bet that DDG either gets the information for free, or essentiall

The details of DDG's arrangement with Bing are obviously not public. However, it is a very safe bet that DDG either gets the information for free, or essentially for free, simply because to do otherwise would make no sense for Microsoft. Microsoft benefits from anything that even potentially reduces Google's market share, by any amount. Of course, that puts DDG in a dangerous situation, since it depends on Microsoft. Perhaps it has a long-term binding commitment from Microsoft, though, that wouldn't surprise me either.