The 'standalone' version is actually US$30. That is the same price as Affinity Photo for the iPad - an app that won the coveted 'App of the Year' award, and is developed by an entire team of highly-skilled developers in the UK. When you consider that WhiteCap - as well as the other visualisers the developer produces - is produced as a hobby, by a one-man band, in his spare time, it is blatantly obvious to everyone that the pricing here is utterly unrealistic, and will turn away most potential buyers.
The irony here is, that if the developer decided to price them reasonably - say, at a US$2.00, the price of a 'normal' game or art app that will entertain you for a couple of hours - WhiteCap (and his other visualiser offerings) would probably be MUCH more successful, and would be likely to collect very positive reviews. He has indeed been developing these visualisers for a couple of decades, so they have now evolved to have quite stable, solid code. They are hypnotic, and nice to look at - for fifteen minutes or so at a time - and would be WELL worth a US$2 price tag.
When reviewing any product, however, we have to take into consideration whether there is value-for-money to be had, and at the current price point, the answer is a very unavoidable 'NO'.