This was posted recently for £2.49 - must be the last few left now at only 99p - what a steal!
Stylish leather wallet with belt clip.
Stereo headphones with volume control.
In-car power adaptor.
Ergonomic handgrip with joystick control.
They also have the Gameboy Micro kits for 99p:
Essentials kit includes: Console storage case with neckstrap, stereo earphones, 3 x screen protectors, micro to micro link lead for 2 player gaming, 3 x plastic game cartridge cases and wrist strap.http://www.argos.co.uk/static/Product/partNumber/5679632.htm
This is a clearance line, so is reserve and collect only, and will be very limited - I know they have some SP packs in Swindon (my nearest store). Best of luck!