This may be an uninformed question, and if it is please forgive me for being somewhat new here. New, as in the very first post.
I've been flying a DJI product for aerial mapping, and while the hardware and software has been excellent, the quad-rotor platform falls woefully short of being adequate for my purpose due to too-short flight times and inability to cover enough acres in one flight. So I'm building my own fixed-wing platform and looking for the appropriate hardware for it. I have studied the online documentation for ArduPilot and when I click on the links that says the hardware can be gotten "here" it comes up "404 - Invalid Waypoint - Return to Launch". This is on the 3DR Store.
So my main question is, where or who is a reputable US source for hardware running the ArduPilot platform? The closest thing I've found is some sources on eBay, or online vendors like Hobby King that have a PixFalcon Micro PX4 unit (that's missing some of the peripherals). So if I could get some recommendations on hardware sources, it would be much appreciated. I don't want to buy something online and then find out it is poorly built and the documentation that comes with it is written in a bunch of squiggly lines I don't understand.