This design is based on one of those big alpine horns, except in this case the design has been created especially for the iPhone. It amplifies the audio from the iPhones own speaker, so there are in fact no mechanical parts in the horn. It comes in black or white, but for the iPhone owner who wants to show off a bit more, then there is this Megaphone finished in a gold colour.
These are the details on the Megaphone passive amplifier for the iPhone;
Acting as a passive amplifier for your mobile’s built-in speaker, this great fluted instrument is ideal for listening to music, holding conference calls or communicating between mountains. Oh alright, it’s not that loud, but it does have a surprising effect on your iPhone’s output. And all without any moving parts.
Priced at £400 ($635), however the gold version is more expensive at £600 ($952)
Source [Coolest Gadgets]