There will be no spare chips for existing Amigas. You would need special FPGAs with 5v tolerance and such a chips would cost over 100 Euros. The plans are for making a cheap mass product like an Amiga Joystick with some Games and a small nano-itx board (for around 200 Euros). The products will all have a one chip solution but without Zorro/Clockport/CPU-Slot for existing hardware.
About the chip designs...the patents of the original chips are already gone and CloneA acts like an emulator in hardware so there is no need for license. Everything is done by reverse engineering. The only problem would be the software including the kickrom but there seems to be a solution already for the kickrom. There are also talks to game companies.