Last time I saw a price for a real VCS3 or AKS it was $10-15k USD.  There was an official EMS AKS VST years ago but it was like E400.  
 
I have the XILS stuff.  It is cool, but it sounds nothing like a Synthi (VCS3/putney).  
 
I have tried  Reaktor program to replicate the VCS3 and was very disappointed.  
 
Specifically, I am looking for the types of FX that the Synthi can do.  I really do not care about its ability to track a monophonic tune.  I am looking for Pink Floyd, Hawkwind, Eno... types of sound effects.  
 
Anyone with experience with comparing a real VCS3 to any of the plugs?  
 
Thanks

If you find one, let me know! The best I've found are a couple of old freebie FXpansion ones (Mysteron and Enigmatron) but they're nowhere near as complex as a real VCS3 and I'm not sure if they're even available any more (they're 32 bit too for reference). You won't get In Search of Space out of them, but I've used them, heavily effected, for some reasonable wibbly-ness from time to time.

Thanks
I have a friend that has a AKS and I know how to patch (pin?) the thing to get what I want.  The XILS thing looks like a VCS3 but it does not do the fx like a VCS3 at all.  

If you have an ipad apeSoft's iVSC3 is pretty good - and not expensive.

Not just good sonically, it's just as awkward, obscurist and baffling as the real thing as well.

I have heaps of admiration for the likes of Del Detmar and Tim Blake who can actually make music using the things :-)

Edited to add - more recently they've added options to make it a bit more, well, understandable. You can ignore that stuff if you want.

nice to read the hawkwind boys getting some props :-)
but no, i can't recommend anything other that the XILS thing either :-/
edit, google threw up some things to check:
http://blog.wavosaur.com/free-ems-vcs3-synthi-aks-vst-emulations/
https://musicandrecordingtoolbox.blogspot.nl/2008/09/vst-discovery-special-feature.html (#18 on the list)
http://kx77free.free.fr/English-page-vst.html
most of these seem quite old now, maybe u-he should do one?

The KX77Free ones are SynthEdit which have reliability/compatability issues (or used to).
 
I'd forgotten the VCS5 by Richard Brooks - I've used that one (once) and liked it...although it too is SynthEdit, as are most of them.  Ho hum.

In case anyone cares, I've also hunted for VCS3 samples and have had very little luck - the ones I've found have basically sucked and aren't particularly FX-y either (they're usually percussion-type sounds).  I've got a couple of samples from an ex-HW member and they are excellent, but only a couple so re-use becomes an issue.
 
I had a chance to buy a real VCS3 one about 20 years ago for around £1000 and turned it down :-(

KPerry
I had a chance to buy a real VCS3 one about 20 years ago for around £1000 and turned it down :-(

just to join in the commiseration, i sold my sh-101 about 25 years ago for 90 quid :-(

space_cowboy
Last time I saw a price for a real VCS3 or AKS it was $10-15k USD.  There was an official EMS AKS VST years ago but it was like E400.  
 
I have the XILS stuff.  It is cool, but it sounds nothing like a Synthi (VCS3/putney).  
 
I have tried  Reaktor program to replicate the VCS3 and was very disappointed.  
 
Specifically, I am looking for the types of FX that the Synthi can do.  I really do not care about its ability to track a monophonic tune.  I am looking for Pink Floyd, Hawkwind, Eno... types of sound effects.  
 
Anyone with experience with comparing a real VCS3 to any of the plugs?  
 
Thanks

It sounds nothing like it?   Really?
 
https://www.youtube.com/watch?v=ghy83NO1SYI
 
I couldn't find it on you tube but computer music magazine had an article and videos where they showed how to create a generic version of the "On the Run" type of track.  It was certainly ball park.

Not the answer you're looking for, but for what you're asking you might consider putting together a small modular HW system, assuming you know how to patch up what you're after.
 
I know the filter is available because I happen to have one:
 

 
It is a whole different thing and it ain't cheap and it's not what you want if you're looking for repeatability, but ...