Kindle is not just subsidised by ads, the business model is based on the fact that you are going to buy ebooks. I wouldn't be surprised if the non-ad-supported Kindle was also being produced at a loss, just like the ad-supported model.

You are right that $185 might be a more realistic pricing, but that's a 68% increase over the price of the $110 Kindle so I wouldn't say that they are similarly priced.