What makes an expensive speaker expensive

Cost is what the market will allow. I've heard several speakers that are over 50K and if I had the money I would buy them. 

I would tend to agree with ricred1.  Some folks may not be in the US and understand the free market system though.  I full understand that part of the equation, but I'd think if you were on a board like this, you would understand it.  

Hi analoguvr,
Despite having the privilege to hear speakers that utilize various types of "exotic" materials for their drivers, paper implemented properly is still preferable to many listeners. High quality paper cones sound exceptionally natural. Personally I’d choose this option compared to an ultra detailed analytical sound. Paper cones and tubes for example never measure as good as their alternatives but they sure sound very much natural and realistic when done correctly. There are non paper driver speakers that sound very well without question, I just do not find them superior to top quality paper drivers.  Of course YMMV as is always the case. 
Charles,

I have had this discussion recently with a lot of my audio friends.  I asked them about paper cones and the cost of speakers that use them.  It's funny, but to a person, they feel that some of the top name companies who are still using paper in drivers that are not costly, are just charging a lot due to their name.  I brought up the fact that the cases can be expensive.  I'm personally on the side of not loving paper as I hear the distortion they have as they break up a ton.  I fully respect folks who love them, but they aren't for me.  I tried to take up the cause of the cost of a specific brand that utilize soft domes and paper drivers.  Even a couple of dealers I'm friends with have joked about the true cost of the drivers in the 50k plus speakers.  The bottom line is that there is a market for speakers that are costly or the companies would probably just go under and thats not happening in most cases.  We all like different sounds and there are plenty of companies who give us all what we want.  

Hi Ctsooner,
We can definitely agree that listening impressions are simply subjective and personal.  In this case Analoguvr posted comments that I could truly relate to. Coincidentally he and I also prefer   SET amplifiers so we certainly hear in a similar manner it seems. We're all fortunate that the High End audio market has products to suit a multitude of tastes. 
Charles,