There are some great deals on ebay from time to time for the exact original MF one. But if you go to a dealer you'll get ripped off, you are better off getting off ebay cause a Yamaha dealer will want around �67 plus vat

http://cgi.ebay.co.uk/Yamaha-XT660-R...item20aa97b4c1

or even cheaper

http://cgi.ebay.co.uk/Yamaha-XT660-R...item4cef79f3a0