I just checked the Norwegian postal service, and as far as I can tell, it’s 60 NOK ($6) for a ‘thick’ letter sent to Germany, meaning a letter with the CD inside (without jewel case).
According to the DP a “compact letter” (max length 23.5 cm, max width max. 12.5 cm, max height. 1 cm) costs Euro 1.80 internationally (0.70 Euro more than within Germany). That would probably fit for a CD/booklet without case and some hardpaper for protection.
However if they consider it as a small package and not a letter for some reasons – officially only documents are allowed internationally – the price would go up and since Norway is not EU it is a bit more expensive starting at 11 Euros or so.
Worth a try nevertheless I guess.