Is there a low-end smart watch with a SDK?

[ivoras]

Does anyone here know about any kind of a low-end smart watch (something like this one: http://www.banggood.com/Original-Xiaomi-Miband-2-Heart-Rate-Monitor-Bluetooth-Smart-Bracelet-p-1057324.html) with BLE, which has an official SDK or reverse-engineered firmware with source which would enable creating custom apps *for the watch itself.*

So, I'm not directly interested in SDKs for Android/iOS/etc apps, but specifically for writing apps directly for the watch itself.

Pebble is one obvious choice, except it's way too expensive for my purpose. I'm thinking there must be some kind of a cheap Chinese smartwatch which allows my code to run on it?

[awallin]

http://www.ohwr.org/projects/f-watch/wiki

 

[hendorog]

http://www.ohwr.org/projects/f-watch/wiki

 

Ye gods thats one hideous watch.

[dferyance]

What is the reason you want it? Is this just something fun to play around with or do you have another goal in mind.
A few years back I made my own by dead-bug soldering a bluegiga ble113 to a sharp memory LCD and coin-cell battery. Used Apoxie Sculpt to create the case (I don't have one of those new-fangled 3d printers).

There is TI's chronos. It isn't BLE but does have wireless.
 There is also MetaWatch: https://www.sparkfun.com/products/retired/12005. Not BLE but has bluetooth.