iPod, Zune, Sony, clone .... whatever.
Honestly, any of these work:
http://www.amazon.co.uk/gp/redirect....creative=19450
Look at these low-price iPod clones:
http://www.amazon.co.uk/gp/product/B...SIN=B002ZXI7P0
That's the black one. Comes in a few colors (pink, blue, green, etc).
These all work. You're mostly paying for name brand and extra features, on something like an iPod.