There is a reason the GC is so cheap and that is because anyone wanting to develop for the system must stump up a considerable amount of money (as opposed to a licence developers must buy the media (optical discs/cartridges etc) from Nintendo). The system itself is sold at a loss.
Nintendo are renowned for being particularly ruthless towards anybody developing unlicensed products for their systems and do not hesitate to take legal action against anyone doing so.
This would have to be taken into consideration for anybody seriously considering porting OS4 to GC. What would people rather have: a legitimate, licensed product endorsed by the manufacturer of the hardware it is to be used on or an illegal hack? That isn't the way to see Amiga products on the shelves of your local PC World.
While I agree that the A1 board is expensive it is also equally true that if Eyetech had produced millions of units they would have been relatively cheap. But would they have sold? I know I wouldn't have taken that gamble.
After all is said and done, and if everyone is honest, we would have to agree that the A1 has been a wonderful and remarkable experiment which has been powered by peoples love of the Amiga and their refusal to see it die. Given the choice of buying Nintendo hardware or Amiga hardware to run OS4, I'd rather give my money to Eyetech.