I think it is a fair price.
I other posts, we argued about smartphone produces being profitable. @nils specifically mentioned LG as an example. LG was able to increase it’s profits (in the smartphone division) in the third quarter 2014 and the first quarter 2015, for example. However, this was only after 3 successive quarters of operating lost. Interestingly, LGs successes is specifically related by LG and press to it’s Flagship smartphones LG G3 and G4. Which came to market with a price around 599€ and soon settled for around 530€ (see the german price trend for reference). And, while LG planned to sell 500.000 units, the profit was made possible because they actually sold well ofter 900.000 units at a time price of the phone was still over 500€! The current top model, the G4 came to market at 650€ now settled for around 500€.
This is just one random example, it is not a valid scientific assessment of the smartphone market. But for it is an indication. Most companies to not release very detailed numbers, but is known that a lot of companies operate at loss and it seems only top models a profitable. Sony for example, while getting great reviews for their top model, have operated at loss since several quarters. They targeting that by focusing on less devices and their Xperia Z range. These are generally considered a good deal for their price, but on the other hand, Sony has a lot of financial reserves and they can go for market share over profit.
Another aspect often ignored is the (hopefully) increased lifespan: If the Fairphone2 will work for 5 years, it is fair if costs more then a device that only is usable for 2 years. I know usable is very subjective: For some it is calling, occasionally browsing and email, for other it means most of the latest and greatest apps run and games can be played. This is one reason for me to assume a lot of users will go for a more recent device in the future (possibly a FP3) and FP2s will go into the second hand market.
Then there is the idea of swapping the processor for a cheaper model. I think the problem is: The experiences with the MediaTek processor make it impossible to go for a very cheap chipset which can not be profitable serviced by the manufacturer. And then, the Snapdragon used in the FP2 is neither the most recent, nor the most powerful chipset on the market and i suppose it is by far not the most expensive. It is a powerful chipset, but already a compromise (a good one i think except for missing 64bit support, but that is another story;-)). In a PC you can simple swap the processor the reduce the price: Swap the Core i5 for a Core i3 or even a Pentium and you can save over a hundred euro with a otherwise identical PC. This is not possible in smartphones. Not only are devices as a whole far mor integrated, the chipsets are as well. Typically, Processor, Graphics Processor, Modem and more come in a singe package. They have interfaces for Cameras and Storage. So if you swap the chipset, you need to make sure the rest stays compatible. You also either do not save so much or must sacrifice on other hardware aspects as well. But the most important problem is how tightly coupled hard- and software is in the smartphone world: The Android distributions are specific to one device: They must be build with right configuration and drivers. That means, two different chipsets means two different Androids Fairphone must maintain, at least to a specific degree. And then there is modularity: If other manufacturer should be able to offer a new camera module, for example, these must work with every Fairphone 2 out there, reducing the number of possible replacements. Then there is volume: It would required two production lines and reduces the volume of devices for each lane and the volume of each chipset bought. In summary, i think all this will pretty much the price reduction due to a cheaper chipset away.
All in all, the more i think about it, i come to the conclusion that the price of the Fairphone 2 is fair and adequate.