Phil – I bought a cheap Ti frame off ebay about 18 months back. It came all the way from HK and cost £350 delivered. The company that was making them also make the frames for Van Nicholas (and what was Airborne). Mine was a geared model though.
In summary, the frame has been just great. I’ve “raced” it at SITS, used it for local routes and been off camping in the Highlands with it (panniers and all). It’s not let me down yet, the finish and welding look great.
Now then – for £650, you might decide not to take the risk that I did. If so, you might want to look at a Van Nicholas Zion as that’s probably the cheapest SS Ti option.
If you want any other info, photos etc, let me know.