I was looking at the Scirocco great machine very exspensive at the time though. By far the best machine I saw was the Tulipo, this is a really high tech beast. The only draw back with it is that it is a 3 phase machine. If you can cover the cost of getting 3 phase into your property then consider it.
I am not sure about its tower height as well. Cant go above 15m but is computer controlled and may get a good output for you.
What stage are you with getting planning permission?