Verified answer

Dresden to Frankfurt on the train is 29 euro if you get the advance savings fare. On days and trains when the 29 euro fare is sold out, there is another savings fare at 49 euro that was still available on every train I checked over the rest of the month. I sampled several days and discounted fares are available starting this Saturday to the end of the month and beyond. There's also a 1st class special at 69 euro which is almost always available and is cheaper than the 82 euro normal 2nd class price. There are a lot of trains from Frankfurt Hbf to the airport - the Sbahn will be cheaper than the ICE trains which cost 11.50 euro.

http://reiseauskunft.bahn.de/bin/query.exe/en

The Bus or the train.

The bus is a long trip but only costs about 1/2 what the train costs. The train can get you from Dresden to Frankfurt in four and a half hours and will cost about $149.00