[fjtorres]

Another reason for the higher price point is sales volume.

All products come with certain associated fixed costs that must be allocated across all the units sold. These fixed cost charges will be lower for high volume sellers and higher for low volume sellers.

The six inch screens are a high volume product because of their lower price point and the lower price point is possible because they sell in higher volumes and thus have lower per unit fixed costs. There is a sweet spot where price optimizes sales volume and profit.

For a larger screen, the sweet spot will be different because they are intrinsically more expensive to manufacture at the same volume. This higher price will result in lower sales and higher fixed cost charges leading to a further price hike which will in turn lead to a lower sales volume. This feedback is why there are so few large format readers and the few available are "disproportionately" expensive.

It is also why the mid-size readers are marketed as premium devices; adding features raises the manufacturing cost but the added value will position the device for a different market that is less sensitive to the higher price. The price is higher but so is functionality.

It's like cars: family cars are priced lower than sports cars or luxury cars because they provide different value propositions. Family cars tend to sell on utility; sports cars on performance, looks, and thrills; and luxury cars sell on comfort, convenience, and exclusivity.

Different uses, different markets, different prices.