I've been using an Alfred workflow called DuckDuckGo with Auto Suggestion. It's works great and returns autocomplete suggestions from DuckDuckGo then passes the results to search DuckDuckGo. My only complaint about the extension is the lack of direct support to use DuckDuckGo's clever bangs.
To perform a normal DuckDuckGo search, simply use the keyword "s" followed by your search. Like "s what is life" to search DuckDuckGo for "what is life". You will get autocomplete suggestions as you type. If no suggestions are returned, pressing enter with search DuckDuckGo for exactly what you have typed.
To preform DuckDuckGo search using bangs, use the keyword "!" followed immediately by the bang term then your search. Like "!yt colin's bear animation" to search YouTube via DuckDuckGo for "colin's bear animation". You will also get autocomplete suggestions as you type to search bangs. While you can still do something like "s !yt colin's bear animation", this workflow makes it a little easier to use bang commands.