I just finished my latest sample library of an old melodica. It uses the AET filter to morph between different dynamic levels and is perfectly playable via breath controller (but also with any other MIDI controller).
You can download it for free, but if you like the instrument, it would be nice if you fill out a little poll about the quality of the software and your music production method.
You can find some audio demos, the download link and the poll at the website:
PS: You need Kontakt 4 (because of AET)