What makes an expensive speaker expensive

...but what makes the price what it is? 

Marketing

"What makes an expensive speaker expensive..."

=>Expensive parts plus Greed, Ego of the manufacturer (or its followers stoking the fires....), higher marketing costs than others and further excessive mark-up...

(Noone has ever truly accounted for the price of many of these speakers in terms of materials cost, cost of construction, etc... versus their more responsibly priced brethren (I'm talking facts and figures not marketing speak). All that happens is we keep hearing the product name and how that must make it worth it just because it starts with certain letters of the alphabet....not saying these speakers are not worth more but seriously, $100K, $125K and more all the way up to $225K, $250K and above???

"Would you be surprised to see $30,000 speakers "outperform" $150,000 speakers?"

=>No I would not as I've heard it from a few speakers (not just the brand I own) at shows and other listening environments and every day I hit play at home with a $20K speaker with a good system behind it :-)

MartyKL and others state a lot of good economic/market-pricing fact above but if you look at the analogies, the difference between a Lexus and a Toyota (fully configured in both cases) or Acura versus Honda (Accord fully blown out...), Nissan and an Infiniti (or other myriad examples) is "X"% in the single or low double-digits whereas high-end audio and speaker markup in particular is usually in the higher double digits (IMHO don't shoot the messenger) or more! High-end audio manufacturers should follow more traditional and conservative market-pricing models and apply a reasonable markup for premium quality; they might very well sell more :-)

There is a lot that can go into making a good speaker. Both the sound and the aesthetics. Also the reliability. In the end willingness of customers to pay for whatever reason is mostly what determines how expensive a product is, including speakers. Values differ by person so anything is possible. The goal of marketing is to help make people more willing to pay for advertised benefits by appealing to the values of the target market segment. The more one is willing to pay the more profit per unit. Thus high end audio was conceived, a boutique industry where units are fewer and  prices generally higher.

"something tells me a lot of mass market gear and plasma tv’s underwrote some of that"

Maybe the mass market stuff did, but Pioneer stopped making their Kuro plasma TVs in 2009 - they lost money on them despite being the best plasma TV on the market, bar none.