Several of these low priced Pi clone boards will work.
I used a Pi Zero W which has Bluetooth and Wi-Fi on board.
This mod works with any build version of the CM15A, although the newer boards allow for more space giving more possible mount locations or a bigger board.
This mod means CM15 doesn't need batteries nor does it need to be connected to your PC ever again(although you could if you wished)
This mod requires no soldering skills, your only modifying the case.
The case mod takes about 1/2 to 1 hour.
The Pi Zero costs under $10, the 5 volt 2.5 amp power supply actually cost me a bit more.
Since the Pi runs Linux any HA software which supports the CM15A will work. Add the HA-Bridge (software) to the mix and your CM15A also becomes a X10 hub capable of handling Alexa requests.
A full write up with pictures can be found here:
http://forums.tuicemen.net/index.php?topic=1291.0This setup is out performing the CM15 AHP combo for me so far.
Sure the WM100 has better PLC strength but this does all 266 X10 addresses as well as X10 security codes.
I can access from anywhere and don't need a phone app though most of the available softwares has one available.