I can't recall the source of how much Google makes per CPM on average, but it's significantly higher than all other search engines. If the deal is cheap/value for anyone, it's Google. It may have been in the UK CMA report on search/online advertising, IIRC it was between $30 and $50 CPM with Bing on around half that.

If my arithmetic is right, 1.5bn searches would increase DDG's number of searches 15 fold. It would seem only Bing is potentially capable of putting in a bid similar to Google's.