PaulRivers

It's my understanding that back in the day, (if they existed yet), batteries were poor, expensive, and heavy. Dynamo hubs let you get a very small amount of light, but it was *some* light, for riding at night.

Eventually battery technology improved - greatly. Dynamo's became basically worthless for the average consumer. They had some niche uses - people would use them for 24 hour racing where batteries that lasted all night could be impractical. But on average - they put an incredibly crappy amount of light, they were very expensive, while battery lights were much cheaper and also put out more light. I mean a cheap AA battery light put out the same amount of light as a dynamo - they were pathetic. They were kind of like Ham radio, Records, or using Horses to get around - they had some niche uses (ever tried to drive a car where there's no road? horses are better at it), but they became mostly fringe.

Sanyo seems to be the only company that was making dynamo hubs at the time. I'm sure they made great hubs, but they charged a premium.

Then LED lighting came along. Even the first ones weren't that great, but every couple of years they got more efficient for the same power. While this greatly improved battery lighting, it revolutionized dynamo lighting. It was only a few years ago that the Lumotec Cyo came out, which in my opinion (having tried the 40 lux version of their other light), was the first dynamo light that actually put the kind of light that you needed on the road.

When LED lighting came around, to my knowledge, before that Shimano didn't make a dynamo hub. It wasn't worth it - it was a tiny market that wasn't going anywhere. But with LED lighting, suddenly, things were a lot more promising. Shimano started selling a dynamo hub priced significantly less than the SON. Then Sanyo released their hub which is cheaper still (though as mentioned, it's efficiency doesn't really improve when you turn it off, like it does on the Shimano or the SON).

My explanation is simply that the SON used to be able to get a high price because it was a niche market, and nowadays they just haven't changed their pricing. It's like the Lexus of dynamo hubs - it's cool, but for many people it's not worth the price premium. If you're interested, Peter White lists out efficiencies on his page here -
Shimano DH-3N70 Dynohub from Peter White Cycles (Those figures may be old, all I can say is that they seem to be done at the same point in time.)

I don't know that much about the Supernova or Shutter Precision hubs, other than that I never hear about them, so I assume they're not revolutionary or anything. I've had trouble even finding either for sale in the US - I heard about them a couple of weeks ago, but could only find them for sale in Europe.