I'm not even sure how much FPGA Arcade or Minimig costs but to be honest this whole FPGA thing is a dead end unless Jeri Ellsworth mass produces her system for the equivalent of £50 it's just not worth it.
Amiga is a bit more complex than a C64 in a joystick... Im sure the higher costs involved reflect alot of R&D time, etc... I think FPGA Arcade is around the $500USD markish cant remember.. but at least its not a CUSA $2000 jobbie which is just a regular PCcceee!
Just my thoughts..