Julie, I think I have heard Mr. West comment on this antenna before, some years ago. The antenna is nothing new or magical, and Mr. West sometimes says more than what he is saying, or just what he is saying, if you read between the lines.
As I recall it, he said the antenna was very well made, that he had in fact used one, and that's important because no antenna works well if it takes water damage, etc. But he did not make any comment or judgement about comparable performance or price, and to "read" more about that you only need to know basic antenna design theory. He doesn't do Consumer Reports type comparisons.
There's no $400 worth of antenna there, nicely jacketed and insulated and able to be taken down and moved and raised repeatedly and still work as well as it does on day one. Unless you figure, someone has to pay for low volume hand production, distribution, and retail market, as usual.
You could build the equivalent by trimming some wires yourself for a fraction of the cost, or you could probably outperform it with a permanent installation tuned to your preferred frequencies and matched to your rigging. No matter what antenna you use, the rigging that is unique to your boat will uniquely affect performance and make it extremely difficult for any "one size fits all" solution to work as well on any two different boats.
Antennas all share the same physics, anything that works by "magic" or that isn't described in conventional terms by antenna type and theory, probably is all sizzle and no steak.
But, for the folks who don't want to crunch the numbers and solder the wires...sometimes a well-made "average" performer is still the right product. Sometimes "reliable" is worth having.