I'm a professional sound designer and composer, and have been using Audio Finder for a while now. It's incredible. The interface is clean and easy to use, and the documentation (despite the developer's self-effacing comments to the contrary) is clear and well written. The features are deep and rich - and they WORK. Unbeatable for the price. The ability to preview sounds in the finder alone is worth the price.

In addition, the developer is responsive, and the license is very generous.

I can't recommend this app more highly.