ELM327 China USB
Where to Buy
As of 2017-06 the device is available via EBay for some EUR 10
Usage on Mac OS X
After connecting the USB cable to your MAC you can check whether the device is visible.
lsusb
Bus 004 Device 003: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
On Mac OS El Capitan the /dev/cu device does not appear "out of the box"
The link:
include a download location for the driver. Download the driver and install according to the pdf file included in the download. The pdf as of 2017-06 is shown below: