To be honest, I think the days of the niche are long gone. The world is full of people all looking for that next big thing that so far lays undiscovered, and while there may well be some products that fit, once they are found it's only a matter of days, if not hours, before these types of research tools are digging them up.
That's just compounded with trying to find a niche through dropshipping, because price isn't going to be your friend.
In my opinion, the new niche is (specialty) genre. Meaning if I was going to sell DVD movies, then I would try to specialize with everything in the genre. Movie posters, portable DVD players, even things popcorn makers, trying to make it a complete shopping experience for a customer. I think that also lends itself to product package deals as well, so some marketing avenues there that could be explored.
Anyway, that's my 2 cents worth : )