As always, great info.
I couldn't give you a price really because until your post I hadn't any idea what the going rates were. Carbon fibre really won't be necessary I don't think, weight saving isn't an issue so much as ensuring I get something decent which won't be extortionate.
You say best of the best runs at upwards of a grand and that something costing £100 will be rubbish, but how about the middle ground? How much would I have to spend to get some thing that I won't regret buying? Are we talking 200-300? Or more like 400-500?
What are the factors that make the extra money worth spending? Purely stability and usability? Or things like weight and strength?
Sorry for all the questions, massively lacking in tripod knowledge.