Hey guys, Just registered to tell you that I quickly found a flight from Marseilles to Copenhagen for ~174 euros with Brussels airlines (using momondos search engine). Still a bit expensive, but alot lower than 254. You will make a stopover in Bruxelles both ways this way, but not for too long.
Ryanair doesn't fly to Copenhagen, sadly. I think the cheapest options there are easyjet and norwegian. Ryanair does fly to Denmark though, so if you don't mind some public transportation for a few hours within Denmark, then it MIGHT be an option as well.
Otherwise, the interrail option is a pretty cool alternative way of travelling during the summer, and is exactly what the danes did for TSL4
Cheers.
~stelzig