Try Battery City, (Naff name!) They're in Shefford, only just up the road, sorry haven't got the no. but they're in yel.com if you do a search under that name, or Shefford Auto Parts. They've just supplied a battery for my lads GSXR600 for £20.00 that looked identical to the original on the bike, don't know about Duke battery prices though. Regards, Pete