They are expensive compared to traditional LCDs, you can easily buy a portable 13" 1080p monitor that includes all the parts to hook it up to a computer, a plastic case etc. for less than $200. Heck you can even get a 2560x1600 one for less than $200 taking a quick peek at Amazon.
The economies of scale applies here: E-Ink panels certainly don't have the same scale in term of sales compared to LCD though, and I don't see this changing at the consumer level.
