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.