My general question is why brushless DC motors seem to be much more expensive than similarly sized brushed permanent magnet motors, especially considering that the construction of the latter is more complicated?
In my concrete application, I'm looking for a brushless DC motor with a 10-15W max power rating. I was first looking for an alternator of that range, but this kind of product practically doesn't exist, I believe because a BLDC fills this role pretty well. Using a BLDC as a generator is a very attractive idea - since you're not driving it, you don't need to worry about ESCs, you just throw in a 3-phase rectifier and you're done (also, it's much easier to detect the running speed by detecting the zero crossings on one of the phases. And some BLDCs have Hall sensors as well, which makes it even easier). Comparing an in-runner BLDC to a brushed DC of similar size, you'd expect them to be practically the same in terms of construction, with the latter adding the brushes and the commutator - you'd expect it to be slightly more expensive. My research indicates that the reverse is true: a decent BLDC fetches upwards of $100 in most reputable electronics shops (e.g. Electrocraft in the UK), even in Alibaba they are $30+ (the price break for 100 units), and even RC-craft units optimized for onesies from eBay are $15-$20. Then you can definitely buy s very well machined japanese brushed motor (e.g., Mitsumi) for a few bucks.
Why is that? Are BLDCs still considered a novelty and economies of scale do not yet apply to them? Or am I missing some technical detail?