Interesting thoughts Whirlybird, but my attitude is quite the opposite.
A few thousand pounds to achieve a lifetime ambition doesn't sound too bad. Stick the money in a special "flying" account when you start and from then on you don't feel you're spending anything.
£100+ a week, £433+ a month, month after month on the other hand sounds crippling. Think of taxiing in on a murky day after one of those depressing lessons where you mucked up stuff you were doing fine a few weeks ago, then thinking, "that miserable hour cost me £100, what else could I have done with the money?"