The BlueFlys are shipped as a completed circuit board with the components listed in the product page. Shipping in this form is much cheaper as it makes the package less than 20mm thick, and I can use the saved time to focus on making more circuit boards.
Bluetooth_USB and USB Model Assembly
See this blog post for detailed instructions: BlueFlyVario_Bluetooth_USB_v12 Assembly
Also see this post for instructions on how you can add a GPS to the USB model (also applies to the Bluetooth_USB model): http://blueflyvario.blogspot.com/2017/08/blueflyvariousbv12-released.html
TTL_GPS Model Assembly
See BlueFlyVario_TTL_GPS_v11 Assembly with the Kobo Glo for an example and links to many other blog posts for other models.
Also see Nev’s page for much more information: http://gethighstayhigh.co.uk/kobo-self-build/