Microsoft Lifechat from Argos for £19.99. Once the pads soften up it becomes very comfortable - the headphones are clear and no one has had any problem understanding me over Skype since the microphone is surprisingly good quality. Uses a USB connection and is plug and play. Worked out of the box with my Windows 8 install and Mac OSX.
Eye, I think they might be need to be shop accessible- Mum has no ideas for my present so she told me she'd get a mic instead of me getting it... So I want quality but like I'd prefer not making my mum pay an arm and a leg- plus she can't shop online.