I have seen threads that mention the new upcoming Alphatron EVF but none specifically about it.
I recently bought a Sony HDW-F900, sans viewfinder, which suited me since I don't enjoy staring through a tiny black and white EVF for very long. Such an EVF would cost $2000+ on ebay and $4,500 new from Sony.

I was looking for an after market EVF when I noticed this in April: Alphatron EVF-035W-3G by TV Logic
It's specs compare favourably with a Sony HDVFC35W 3.5" HD colour EVF which is $12,000+ new.
Alphatron EVF (http://www.alphatron.tv/evf.html) VS Sony : HDVF-C35W : Technical Specifications (http://www.sony.co.uk/biz/product/viewfinders/hdvf-c35w/technicalspecs)
It has some features that the Sony lacks, a 960 x 540 HD LCD(retina display), and 1/4" 20 mounts on 3 sides. This enables the EVF to be mounted via noga arm or such and used cinema style. There is a standard Sony EVF extender for this that costs thousands and is not that satifactory. F900 cinema style EVF extender (http://www.google.com.au/imgres?start=205&hl=en&newwindow=1&safe=off&sa=X&tbm=isch&prmd=imvns&tbnid=Z3SMuqVc2v2VbM:&imgrefurl=http://www.sony.net/Fun/design/activity/product/f23_03.html&docid=WMv5Dv3_kVLMaM&imgurl=http://www.sony.net/Fun/design/activity/product/img/img_f23_03-1.jpg&w=270&h=152&ei=o_y-T7OwGMramAWlxLCsCg&zoom=1&iact=hc&vpx=564&vpy=576&dur=82&hovh=121&hovw=216&tx=140&ty=89&sig=114706493509093178406&page=9&tbnh=110&tbnw=196&ndsp=25&ved=1t:429,r:7,s:205,i:76&biw=1215&bih=910)
The Alphatron is much more flexible and modular due to the 1/4" mounts.
It also has an internal shutter to protect the LCD.
It is little more than half the weigh of the Sony at 480g.

I will be using a TVlogic VFW 056WP together with this as a studio style viewfinder and as a vectorscope/waveform monitor and to view the camera's menus since the one feature that the Alphatron doesn't share with the Sony is component input to enable viewing the F900 menus and to display timecode, f number etc.
Otherwise the Alphatron has all the pro specs of the Sony.

It's satisfying to find a solution like this that is much cheaper and significantly better than a genuine part.
At $1395, I'm looking forward to the Alphatron EVF.

I believe the first units will be shipping in the next week or so. It really is a great EVF. I'm getting one and will post a full review of the production unit as soon as it arrives. I've used the Sony C35W many, many times and although I couldn't compare the two side by side, I would say that the Alphatron is just as good as the far more expensive C35W. I don't however like using Noga arms and similar for EVF's as they do tend to droop and this often results in the EVF's horizon not being level and this can easily lead to wonky pictures.

@Alistair
"I don't however like using Noga arms"

Thanks for the comment.
I was wondering how it might work.
The VFW 056WP I have is mounted on a cheap Noga style arm and it does droop and this makes it hard to get it level.
And that's without having to put my eye to it.
Any suggestions for something more substantial?
I though I saw a hint of brackets for the EVF 035W.

I look forward to your review Alistair.

Alphatron EVF-035W Viewfinder Review with Alister Chapman

Alphatron and Genus are bringing out dedicated EVF support kits for 15mm rods. They are both similar, the Alphatron one specifically for their viewfinder.

The wait for the release of the Alphatron is over.
Not sure how it made it to Australia before the US, but great!
My Alphatron by Kieran Steele (http://www.dvinfo.net/forum/view-video-display-hardware-software/508758-alphatron-evf-mounts.html#post1743307)

$1705 though:
Alphatron EVF (http://www.lemac.com.au/products/alphatronEVF.aspx)