Why are DAC's so much more expensive than transports?

I am going to be a bit of an outlier here and feather ruffler. I had a friend one time who was a bit on the wealthy side. He had a very good education and a very good business. He traveled extensively. He took a trip to Europe with his wife and she wanted to go to France to have some fine wine and possibly visit the Louvre Museum. So when he got back and we talked about his trip, he said he had a good time but he couldn’t agree with his wife on the excitement and great experience his wife had with the great wine and museum artwork. He told me he does not understand all the fuss about the wine and really could not get the “Mona Lisa”. He told me the painting was not impressive. In that instance I knew how undereducated and shortsighted he was with regard to art and culture. He couldn’t grasp the time, effort, talent it takes to make great wine and didn’t know much Leonardo da Vinci and his overwhelming engineering, creative and artistic talent. So what does this have to do with a DAC? Well I guess it means the companies, engineers and talent that goes into the making of a great sounding DAC would often get overlooked.

@carlsbad2 : I disagree that DAC's are evolving. DAC's have been transparent to the source for decades. They are solved engineering! The expensive prices are money grabs by the greedy. A DAC is essentially the equivalent parts-wise of a computer soundcard. Manufacturing efficiency has driven down prices for soundcards. The same can be said for all the millions of DAC's currently in use in CD/DVD players and streamers. Manufacturers that claim they have some secret circuit design that distinguishes their "audiophile" DAC's from the majority are preying upon the gullibility of the unwary. 

verdantaudio

... if a unit is fully balanced it effectively doubles the circuitry as well and this adds a lot of cost ...

That's a common misnomer. Many truly balanced circuits employ circuits such as differential amplifiers, of which operational amps are an example.

The only evolution in DACs that I see (and really interested in) are FPGA implementations. A different tube, chip, casework, etc are not that groundbreaking with DACs. 

DAC's are the component that determines the sound character. So, the amount of effort components to carefully craft the sound vs just spin a disk and stream the bits is simpler.