Hi, I’ve compiled a full tutorial on running Pi Aware (you can add FR24 and feed other excahnges) using Orange Pi. These boards are Raspberry Pi clones, and when using armbian (not Raspbian) as operating system - proved to be nearly as robust. This brings down the cost of the tracker to sub $30 region with mSD card, Irange Pi One/Zero, T2 stick and own antenna. Written in English and Polish, enjoy: goo.gl/kOMUrs
Also - if you want to build FLARM receiver: goo.gl/X8tcD4