I would buy one or two. :)
Friday's Fantasy Future Gadget has a very simple premise: we'll give you one of the best ideas ever conceived for free. You have to buy us a jet plane when you make a million dollars with it, though. Today's gadget would sell, like, eight nine eleven millions or thousands millions in a week, guaranteed.
The premise is simple. Someone needs to purchase the rights to use the image of Soundwave, the evil Decepticon Transformer, from Hasbro. Then make a hard disk-based MP3 player out of Soundwave (slightly smaller than the original Transformer toy, though, for portability) that actually transforms. Then sell the individual transforming cassette Transformers (Casseticons, was it?) as individual USB flash-based MP3 players that can be placed inside the larger Soundwave unit to extend its library.