Helical bladed Gorlov type VAWT.... any experience?

Hi all,
My house is well-sited for small scale wind energy collection, and I'd love to toss something like a "Turby" on my roof. Unfortunately, no-one stocks or sells small-scale VAWTs in Australia, and even those relatively readily available overseas are still rather unfortunately (i.e. ridiculously disproportionately) priced.
As I am pondering the merits of heading down the DIY path, I was wondering if anyone out there has had much experience with the aerodynamic side of things with regard to lift-type VAWTs, and helical blade designs especially?
Cheers, Chris