The saebrtrack from AMSATs own Mark Hammond is probably the best documented DIY board. The processor is a bit expensive and slow but the one I built does work. I had a FoxDelta ST3 for a while but had problems with it right from the start. I was able to return it without any trouble. It is probably the best deal out there. The easiest part of building your own is the software. The program does not do much so it is straightforward and easy to write. An lcd display of some type is invaluable in troubleshooting but you can use a terminal emulation program on a computer for set up. The buttons are not needed if you have a G5500. The case and cables are the most work.
http://sites.google.com/site/marklhammond/saebrtrack
The LVB Tracker from AMSAT is great in that you can "have it your way". Buy only what you need from a bare board to a completed unit. It is also a nice way to help out AMSAT.
http://www.amsat-na.com/store/category.php?c=Hardware
Sent from my computer.
73 W9KE tom ...