Oh, I understand the distinction between, say, a £40 or so scope and something in the £2-300 bracket (ie. around half the cost of a good rifle). But beyond that? There must be very few shooters who are good enough that the additional quality of the scope will make the blindest bit of difference.
A high end piece of glass will only make a difference once you're shooting is already very, very consistent. Before then, inaccuracy caused by the shooter will mask any minor gains caused by the scope. The simple analogy would be that buying a Ferarri won't improve your driving: you'll only get the best out of it once your've become an extrenely good driver. Up til then, probably best to stick to a Focus...