What makes an expensive speaker expensive

Hi ohlala, 
I didn't address ctsooner's comments about paper cone "breakup" as I want to avoid going too far off topic  (which is easy to do ). No matter the driver cone material of choice there's always a hierarchy of quality and performance.  Designer talent, knowledge and most certainly implementation are the determining factors. 

Paper cones done poorly will have obvious failings, if done right they'll sound wonderfully natural. Carbon fiber, aluminum, beryllium  etc.  The same principle holds true,  there's good and bad examples of all materials. 
Charles, 

ohlala
They vary depending on which speaker. The range is from $136.00 to $2700.00, but that is the cost for rebuild. New drivers are not priced out. 

Paper cones are always in break-up at all frequencies, but because of the cone profile and the fact they are paper, it is smoothed. A lay way to know if a driver is pistonic is if the frequency curve rolls off at the same rate the voice coil inductance increases with frequency. Single layer carbon fiber, woven kevlar, poly and paper have very low frequency break-up modes. The shape of a cone is primarily to smooth and spread out the break-up modes for smooth response, but does not eliminate break-up. Early articles done by Celestial, when metal tweeters first came out, compared them with soft domes which break-up at approximately 8K.

I just wanted to get you an answer, but this really has gone too far off course for this thread.  Sorry for the hijack. I will stay on topic.  Again, sorry all.

Darn, I'm sorry, but it won't let me edit a post that's over 30 minutes old. I forgot to answer you on the drivers.  Their drivers come from ScanSpeak, but they don't have part numbers as they are not standard models. All of them are custom or use custom components made by Vandersteen like baskets and cones.

Ctsooner you can have great impact with a SET depending on which one you are listening to. Also as long as the speakers are a proper load. I use 845 with paper driver tannoys and the impact will blow your hair back. And I find the bass to be much more natural sounding than SS bass. It sounds right to me, not like over damped Ss bass.. Especially when you are listening to a standup bass. The harmonic overtones you get from a SET can't be equaled. YMMV. We get into trouble with generalizations like SET doesn't have impact or do bass, or paper drivers do this, or whatever.....

Well, if we are now talking about what makes an upgrade expensive, I read online, but never verified myself, that B&W has a couple of very closely related lines.  The higher end line is identical except for a Mundorf MKP replacing the default polyester tweeter cap. About an $7 upgrade (retail) for a couple of hundred bucks in MSRP for the speaker. 

Best,

Erik