I've been getting my Pixhawks from Hobbypower, ordered thru Amazon. I hesitate to post a link as it might be viewed as "advertising" for a particular vendor. But you can look them up easy enough on Amazon. They have the board, M8N GPS units, telemetry radios, etc.. It takes ~10 days to get it here from China, but everything has always been as advertised, and it all works.
As far as I know, the Pixhawk Mini is just the PixFalcon PX4 that was originally developed by HobbyKing and sold by various vendors like Bangood, etc.. I've been flying a Pixhawk in a 700 and 600 heli, and the Pixhawk is kind of big with not a lot of mounting options. I've had some problems with mounting it underneath the heli with "noise" from the ESC and motor only 1cm away on my 600. The 700 is a nitro heli so don't have that problem on that one. So I ordered a Pixhawk Mini from 3DR for it that I can mount on top of the tail rotor drive case. It comes with M8N GPS, etc., and looks to me like the spittin' image of the PX4 sold by HobbyKing. It's 38mm wide and just fits inside the main frame on top of the tail drive case, and other than the connectors is the same internally as the Pixhawk 2.4.8, I'm pretty sure. I figured I may as well get the "kit" from 3DR then I know all the connectors match. Although I did have to order a 6S power module for it separately, which is the same Crius 6S module I get with the Pixhawk when I order one from Hobbypower.
So I think 3DR is not making anything. They are just a reseller now.