Spuddy, there's a Specialized that I converted to single speed hanging in Walkers Wheels in Montmorency. Brand new and never ridden and pretty cheap I think.
I have to warn you that it was the first SS conversion we did and while it isn't going to break anytime soon (big solid horizontal drops like the On-One Gimp jump bike) it also isn't the prettiest piece of engineering you're going to see. Might help you out though. Call Marcus on (03)94322113