Honestly, $50 is not expensive for a DIY device. If you were to purchase the main components separately, you could expect to pay about $30:
2.9inch E-Ink display module: $18.99 [1]
Wemos D1 Mini 8266 module: $2.55 [2]
600mAh Lipo battery: $1.87 [3]
USB-to-serial converter: $1.08 [4]
3D printed case: $5 ?
On top of that, this is a totally custom designed and assembled PCB which would cost any indie hardware hacker a lot of time and significantly more than $50 to produce.
Of course, if you were to get this mass manufacturered, you could probably bring the cost down to about $25 but I love Tindie because it gives makers a platform to share their products and consumers a place to buy very custom products that they do not have the time or money to make themselves.
Thank you spuz, I totally agree. Full disclosure, I'm the guy who develops and sells these modules. I do this in my spare time. I didn't have any experience in manufacturing and shipping products like these before. A very good friend who lives in China helped me a lot with designing and manufacturing the ESPaper modules. Normally in China you'd have a minimal order quantity of thousands not hundreds. But with his help we can do small batches. Small batches are a driver for the price per piece of course. But there are a lot of other costs involved, pure hardware costs are just little over 50%. You get the ESPaper in a nice package with a pretty enclosure. As somebody mentioned earlier payment gateways want to have a share. And to pay my friend in China for his work and hardware I have to transfer the money using Paypal or banks and they open their hands again. There might even be currency conversions involved, depending on the path the money takes. In rare cases a package gets lost on the way to the buyer or it arrives broken and you have to replace it.
For shipping I use a fulfillment service in China. If you order on Tindie I import the order in my own shop system. From there the order is exported together with orders that came in directly on my shop to the fulfillment center by API. I have to choose the best of sometimes 20 different shipping services and the costs for shipping are different for every case, depending where you live and if value added tax is pre-charged (e.g. EU countries). Then a guy in a warehouse in Dongguan walks to a shelf and picks one of my boxes, labels it and sends it off to you. I had to learn the hard way that sending without tracking is cheaper but quite risky. So I also put insurance on the orders. The guy in the fulfillment center also needs to get paid.
And I spent a lot of time developing a graphics library (MiniGrafx) which gives you a lot more freedom than other libraries available for these displays. And now I'm working on a web server application which will make it super easy to configure the ESPaper remotely. Choose a application (e.g. weather, Calendar, Meeting Room, Sticky Note), configure it and when the device wakes up next time it will download the image information from the server. So all that costs a lot of time and most of the code is open source or will be at one point.
I totally understand if you want to build this by yourself, since I am having a lot of fun doing it. But not everyone has that level of patience or expertise and those who don't I'm offering a short cut.
2.9inch E-Ink display module: $18.99 [1]
Wemos D1 Mini 8266 module: $2.55 [2]
600mAh Lipo battery: $1.87 [3]
USB-to-serial converter: $1.08 [4]
3D printed case: $5 ?
On top of that, this is a totally custom designed and assembled PCB which would cost any indie hardware hacker a lot of time and significantly more than $50 to produce.
Of course, if you were to get this mass manufacturered, you could probably bring the cost down to about $25 but I love Tindie because it gives makers a platform to share their products and consumers a place to buy very custom products that they do not have the time or money to make themselves.
[1] https://www.waveshare.com/2.9inch-e-paper-module.htm
[2] https://www.aliexpress.com/item/1pcs-Smart-Electronics-D1-mi...
[3] https://www.aliexpress.com/item/High-Quality-3-7V-600mAh-25C...
[4] https://www.aliexpress.com/item/1PCS-CP2102-USB-2-0-to-TTL-U...