In a nutshell, the IP route is a non-starter really. The reason is that (1) there is no contractual obligation between JW and the pfm investors requiring him to assign his IP rights to the investors; when someone is paid to produce a product for another, the IP rights in the product do not automatically flow to that customer, and (2) JW was not an employee of the pfm investors. As some may know, I am a UK and European Patent Attorney by profession, so I could elaborate, but the basic advice wouldn't change.
The best way of getting redress would be through contract and consumer law. However, the problem is that, for many of us, the sum isn't worth the bother. Most fraudsters who work this form of scam know this and, thus, know they can get away with it most of the time.
An alternative would be to report the whole affair to the Czech authorities, on the off chance that they might take an interest. I have no knowledge of Czech law and have no idea whether this would be worthwhile.
Personally, had I paid for VTEC amps, I would have sued some time ago, as the sum involved would have justified it, but as my investment was £3-400, it wasn't. Organising a large group of people to fund litigation is an administrative nightmare and takes dedication. Maybe someone in for thousands might care to do this. As I have mentioned before, I would be willing to contribute to this financially, but, given my relatively small loss, I would not want to run it.