I have a melodica. It was hells of cheap on Ebay and came with a case and everything. I used it in college to accompany my roomate's dramatic readings of Jewel's poetry.
The more notes you add into a chord, the more breath it takes to sound it. Melodies are infinitely easier to play. But maybe my adorably cheap plastic instrument is just inferior. However, my roomate had a vintage metal one that was too sweet for someone not to steal, and it behaved the same way. I hope whoever took it likes it as much as I did.