I've a USB iPod charger (not exactly the same as that, but not too different, I would presume) that works perfectly well with my Wiz. Was cheap too.
In fact - it's one that looks identical to this - http://cgi.ebay.co.uk/USB-AC-Power-Supply-Wall-Adapter-MP3-Charger-UK-Plug-/220626206616?pt=UK_CE_MP3Access_RL&hash=item335e58bf98