[Pup]

I see that you have put £20-30 and already have had some sennheisers, but from my own experience I would recommend a set of sennheisers to friends (either PC151, 161 or 350).

Only reason for that is I did have some plantronics headsets which were about £25 a set, but I went through a pair a year (have my 3rd set tucked away in a box somewhere) until I decided to plump up the extra money for some Sennheiser PC150's which were £50, yet they have now lasted me well over 3 years plus sounds loads better than the cheaper plantronics.

In my opinion, you get what you pay for when it comes to sound quality and build quality, but whatever set you get you still have to attempt to look after them. If you really want a cheaper set, then I'd suggest looking at what plantronics have, but personally I think they break too easy.