Economies of scale. They are not made in large numbers. I estimate the entire amiga worldwide population to be 10,000 at most and even that might be generous. Hence, the maker of this board (Acube) does need to make some profit too. So does the Amiga OS owner (whoever it may be now). If I started selling hardware why would I sell it if it wasn't worth my time? And no if i drop the price, I want to see 100s or 1000s of orders.
Like others have said: its a small market. If price is too hefty then go ahead and buy the crappy windows machine.
The amiga was never good on the price even with Commodore. And lets face Amiga was never about gigahertz and gigabytes like the PC. The quad core pc may still crawl with vista on it...
HERE is a question: at what price would you say SAM would be competitive??? (much more creative than whining about the current price).