First of all, Vibrandoneon was invented BEFORE melodica, it is only that both instruments have very similar mechanism. Vibrandoneon was invented in Italy in 19th century, where melodica was invented around 1950's in Germany, then the Japanese put the piano keyboard design on melodica. The main difference is that Vibrandoneon has double reed for each note on the instrument, and you can turn both reed on, or one of them on, just like an accordion; where the melodica has only single reed for each note. More importantly, Vibrandoneon is crafted by premium wood. Hence Vibrandoneon has richer, rounder sound than melodica.
But of course, Vibrandoneon is MUCH more expensive than melodica. It costs around US$3000 as I know. Actually for such high quality instrument, the price is not too bad, even I once thought about getting one. However, the reason I did not buy it is that it cannot be played by two hands, which would highly limit the style of playing. To me, I would make way better use of a good melodica like Mylodica or Hammond 44, than a Vibrandoneon, and they only costs US$300 and US$385 respectively. (In my case, since the pickup of my Hammond 44 somehow does not work, I asked the seller to give me US$130 discount, so I ended up paying US$255 for such wonderful instrument LOL).
Anyway, here is how Vibrandoneon looks and sounds. You can definitely tell it is a FXXKING good sounding instrument.