Get over to the Apple Refurb store asap as they are clearing out a huge range of iPods. The 20GB iPod with colour screen (must be the Photo version - EDIT: No just colour. EDIT II: Apparently the same thing as Photo just different name.) is only £69.99! The 4GB mini is down to £60 also!
There is a £5 charge for shipping but if you add another £6.44 to your basket the shipping will change to free. Try iTunes vouchers (thanks A-N-D-Y).
How: Follow the link over to the Apple refurb store and scroll down to the iPod section.
Thanks to bobbertandsammy for the tip!