Breadwinner - new sourdough gadget

I stumbled across Breadwinner today, completely by happenstance. It is intended to allow you to track your starter’s growth from just fed to peak readiness. 

In short, it contains two sensors.  One monitors CO2 produced by the starter and one monitors the starter’s expansion.  The data is presented in the form of graphs.

I admire the geek factor and the outward simplicity of the device.  At the same time, I’m put off by the $85 price tag.  While I can afford it, it’s a bit steep for something that I’ve learned to monitor with my Mk I eyeball.  

Still, it might meet the needs of someone here, so I present it for your information. 

Paul