The potential impact of extoling the differences differences of "natural" red vs "fake" red, then emphasising the virtues and rarity of the former. It can only serve to encourage rarified pricing. £250 per hour? Ouch!
There is some benefit from the effort of sifting rusty waters. Instead of building copper pedestals. 
I don't believe that those two things- 'natural red' and 'higher price' are correlated, either in general, or this instance. She happens to be towards the pricier side of the commonplace range £100-£300 that all London punters deal with: and it's almost certainly as a result of what she feels she can command - on the basis of her desirability
as a whole - it's nothing to do with the scarcity of gingers.
Few people enjoy paying more than they strictly have to: I can assure you I am not one of them. If she is wrong, she will have to lower her prices - as we see many do in response to market demand. I would far prefer that this woman charge much less, and, at some point, she almost certainly will have to: but just right now, she feels in the seat. If that changes, we'll be amongst the first to know, and to get the opportunity to put our money on the table.
Quoth Nik:
Makes me laugh when people think £200 or even £150 is expensive in central London. I don't know what they expect to get for say £80. I have paid £250 and even £300 in the past and received far worse service than Nicoletta (or Michelle).
Yes, obviously price doesn't correlate to service in punting, but believe me you will get fuck all decent in central London for less than at least £120. If someone is charging less than that you immediately think why? Are they a scammer or a skank? What is for certain they won't be any good. I don't care what anyone says, that is a copper bottom guarantee.
There are those who know differently, or might disagree, but about the realistic extent of their lower bounds is £80/£90 - and generally speaking, that is to narrow one's choices down very significantly - you'd currentlly lose 80%+ of the available market for a 1hr apppointment.