Hi Lachlan,
I have been constructing Oz's 6Kw Inverter.
Total cost for all the bits I needed to buy was about £500 GBP.
Oztules notes and jottings are excellent and in my opinion sufficient to produce a good machine. My 'OzInverter' LIVES, and it 'cocks a snoot' at my expensive SMA Sunny Island 6, which never did do what what it says it is supposed to.
My 'OzInverter' is in at present, as I fit all my Meters and finish.
The Transformer and PCB's are the heart, and Oztules way of manufacture is actually straight forward. Commercially winding them at that size is probably just not cost effective.
I will, sometime over the coming winter put my 'OzInverter' construction/manufacture story, into a Booklet form with lots of colour Photographs etc, which may help others.
This is my Not for profit 'Make your own cost effective 2kW PV Solar Tracker' booklet. And I will do something similar with the my 'OzInverter'.
http://www.echorenovate.com/new-book---make-a-solar-tracker.php(Sorry Mods if this link is inappropriate please remove if you think necessary, we are Not for Profit.)
My French sheep checking my installation of No3 Tracker?