The estimated cost is going to be near the $200 mark. Maybe $175.
The problem is that there just isn't a market for it to make it profitable.
This is why most high-end and custom gear is disproportionately more expensive than the mass market versions.
If I were developing this product, I'd price it at $499 (excluding installation), and give everyone who pre-orders in these forums a $100 rebate.
Would that make the economics work out better?
(You'd probably want to market it online to car aftermarket shops and Nissan places, too -- but then, also allow for warranty and returns)