$500 per unit seems grossly overpriced. I don't think that will ever ROI unless you pay in fiat and price per coin shoots up like crazy.
I am not sure it is **grossly** overpriced, but seems like a "list" price that will surely come down, especially in quantity. Power requirements will be very important, but consider that it would take FOUR R9 290 cards to achieve 3Kh/s scryp mining power. Assuming you have a system that can handle four cards, those four cards will set you back about $2,400, plus at least $250 for a 1300 watt gold rated power supply (which might not even be enough, may need two), plus the cost of a dedicated computer to house them and run cgminer. So that is at least $2,650, versus 10 x 500 = $5,000 for these little doo-dads. And, those 10 units of the combo scryp + BTC will mine 80 Gh/s at the same time (as I understand it, yet to be seen). At the current rate of about $10/Ghs, that adds another $800 in value. So I think the apples to apples comparison is $2,650 + $800 versus $5,000.
And then there is the fact that you can (again, according to the original spec yet to be proven; and power requirement TBD) string together dozens of these which would not be possible with graphics cards unless you were to invest in multiple servers (I think the max on crossfire is 4 cards per server).
Overpriced at list price? Yes, but I would not call that gross overpricing. It seems like high end pricing, and I am sure it will come down (especially as price per Gh/s of BTC and price per Kh/s of alt coin mining also drops as it has historically).
