Theo has a few patents -- on the mouthpiece, the ligature, the cap, the manufacturing process.
The one on the manufacturing process is interesting. You can't just machine these for £29.99 anywhere, even China. There is a reason every cheap chinese metal mouthpiece out there is a copy of a Berg or a Guardala -- because
that's what you can make cheap. Machining a large chamber and especially a large throat is difficult -- you just can't get a tool in there. One solution is to use a 5-axis machine. Very expensive. Another is to machine a really long window, (Rovner, Jody Jazz). Theo solved the problem by taking a cue from Otto Link -- Links are forged in two halves then brazed together. Wanne's pieces are machined in two halves, brazed together, then machined again before hand finishing (if needed from what I gather), plating, etc.. Somewhat complicated and rather time consuming process, but he gets very accurate and repeatable results, from a much simpler (and order of magnitude cheaper) milling machine.
Yes, the price is high. But looking at how they are made, and what the wholesale price has to be for his retailers to make an acceptable margin, I'm not sure he can afford to sell them for much less.