Question : What day in the next four weeks has the best fares?
Answer : Since low prices are preferred, look at Feb 27th. As of Feb 20th, it's showing the cheapest ticket sales at $774. That is 44% below the average price for this route, so you can spend that extra money on an adventure in Dusseldorf.
Question : What price range should you expect when booking from Dallas (DFW) to Dusseldorf (DUS)?
Answer : Ranging anywhere from $774 to $4,012, prices for DFW to DUS do fluctuate much more than most routes from the United States. Prices tend to be lower the further out you book.
Question : How long do most people visit Dusseldorf?
Answer : Of course you're not most people, but if you were, you'd stay roughly 17 days.
Question : Is price more important than specific travel days for you?
Answer : The best day to fly on a budget this month is Saturday. Being flexible with your travel days garners even more savings during booking.