Hi Paul,
I bought an ebay DVD/GPS from seller "easydeals636". I just did a quick search, and whilst he doesn't have any listed currently for a Nav, he does have other systems - so you should be able to get in touch and ask for one. I opted for an Aussie seller - but probably a bit cheaper from HK. Paid aroud $500.
He was a really good seller. The unit supplied came with a 90 degree GPS plug, and did not foul the cross member at all - it must be close, but zero problems. I mounted the GPS receiver on top of the dash - a perfect spot in the centre, near the base of the screen.
I've ran the unit for about 7,000ks (4 months) - and overall it works very very well. Only negative is a very faint screen flicker once in a while and bluetooth doesn't pick up voice very well. Maybe look for one with provision for an external MIC - this unit doesn't allow for this (unless hard wired in the unit - haven't attempted yet)
The inbuilt GPS software (not familiar with brand) is very good - and has the most comprehensive pre loaded POIs I've ever had in any device (Bunnings, Kmarts, Motels on the road to Fraser - all there with correct contact numbers). I have come across the occasional wrong road, but very recent changes, so not too bad. GPS signal reception has never been a problem.
The digital TV is rubbish. You'll need a better aerial than the one supplied if you want this to work.
The SD card slot is great - chucked an 8gb card in there and allows for heaps of tunes.
The ipod controler is a bit clunky - too hard basket for me.
DVD/CD and radio works very well - no skips.
Yet to hook up the rear camera - which came included in the kit.
The install gave me some minor problems. The original harness supplied did not suit my Spanish 07 D40 STX. So, I described what harness I needed - and he sent a new, correct one, at no charge. I suggest you take a photo of what you need and send to him before completing the sale to speed things up. Once I had the correct one - it was truely plug and play.
And - by the by - rather than mess around with loading off road maps - I've just downloaded the iPhone app "mudmaps" and download the map tiles I need in advance (for about $3 each) So far, for about 4 wk ends in the high country i've only needed to buy 2x maps! Works great in addition to a paper map. and NO GPS reception required on the Iphone.
Hope this helps!