I think its based on performance, which generally correlates, and can be approximated by, price (not always mind - many expensive items don't necessarily perform better than their cheaper counter parts).
I don't believe it is based on budget, and certainly most people would agree £200 isn't going to be high end (unless we're talking banana plugs!).
I believe that you have to consider the sliding scale of performance/price. If you take the two extremes, say for example the bargain basement budget version of an item might be, for arguments sake say, £20, and the most expensive example is, say, £100,000. You then would logically expect to apportion particular sections if that price range into performance/price categories (such as budget, entry level, mid-range etc). You would not necessarily expect all sections to be of equal size either - most would agree performance of audio items tends to be affected by the law of diminishing returns, which gets more severe the higher up the price scale you go. So for example where the 'budget' section could be £20-£100, the 'extreme ultra high end' section could be £40,000-£100,000.
I'm not sure if that answers your question or whether you wanted someone to actually tell you that, say for speakers, what specifc range might be considered 'high end' and the same for power amps etc etc - that is something few of us are well versed enough in audio gear to answer, and something that is probably going to cause disagreement.
As always, just my 2p worth . . .
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