Taxes from DUS is about $95 where FRA is $115, but FRA does offer 3 flights per day, where there is only 1 flight from DUS. My dates of travel are around Dec 15-22. My friend that I am visiting says she might be able to get a car hire for me for about 30-40 euro's each way...so probably will do that option rather than the train for about 79 euro's each way.