A good ANR headset such as the Bose-X or the Bose A-20 are fantastic and worth the money. But, the cheapest you might get a second hand Bose-X would be around £500.
For under £200 I would personally look at two models that I rate highly. One would be the David Clark's that have already been mentioned, and the other is the Harry Mendellson HM40s. I've used both extensively, and personally see no difference in quality between then, save that the HM's are half the price and not the colour of a badly polluted pond.
Mostly, in light aeroplanes unless they are particularly noisy I tend to use my comfortable and much loved pair of HM40s. In noisier aeroplanes, I'll borrow a Bose from work.
G