The mount arrived today, took 5 minutes set the required height and attach the throttle plate (comes separate so the package can be flatpacked).
It's well-machined and rock solid. I'd say the cost is justified but if anyone had the tools and machining capability they could probably produce one for approximately £50-£60. The key component of this particular mount is the toggle clamp....I had a quick look on ebay and found the exact same one used by Monster Tech (
link).
In summary it's probably worth paying the extra £25 to have a nice light yet robust throttle/stick mount from Monster Tech. I'm definitely impressed.