It's what a free market society is like.
That person that is selling nubs of a Walt Disney for $150 has more than likely spent a lot of time dialing in his system and spent a lot of money on lighting and equipment to be able to grow a desireable/difficult coral. Who knows how many corals that he/she lost to RTN, AEFW's or ALK swings before they finally got it right. There is a lot of investment that goes into high end corals. Over the four years that I've been in this hobby, I've really come to admire those people that can grow those difficult corals and have seen the dedication AND the heartache when they lose a nice colony or even a whole tank to a crash or pest. If you have a local Reef Club, join and be active in it if you are not already. Many of these seasoned coral veterans can be very generous and helpful with coral frags for others interested in the hobby. (or is it the same as a "dealer" getting someone "hooked" for cheap???) For those who don't want to pay that price or can't afford it, there are other corals out there that are still beautiful.
As for the acrylic fabrication.....that is something that I frequently do for my job and quality does come into play there. Material thickness', how are the joints prepared and glued/welded and design are all factors. Of course you can use buckets, rubbermaid containers and the like, but if you need something a certain size or you happen to like high quality and can afford it....then by all means buy the fancy 3 color acrylic dosing containers with the company's logo lasered into the tops.
Pricing will always be like this. It doesn't matter what the product......cars, homes. The more attractive, the brand, rareity, the more options, the higher the price. How many people are reading this on a $1000 IPhone but think $75 for a frag of Holy Grail Torch is ridiculous?