Oil coolers seem to be a bit of a rareity - I remember looking when I was thinking of fitting a second cooler to my big bore 900SS.
  You could try 
http://www.reservoircogs.com  or the dreaded Ebay

 - (search Germany and the USA as well !!!) 
 Demon tweaks also sell nice looking after market coolers if I remember right but they were VERY expensive...  
http://www.demon-tweeks.co.uk/catego...asp?cls=MCYCLE  cooler:  
http://www.demon-tweeks.co.uk/catalo...&fro  m=search  Starter motors.... 
 Erm - I actually have a spare one but sadly, I think I need to hang onto it given all the starting probs I had at the end of last year. 
 Not sure of the differences between models - but they are just as rare on Ebay as oil coolers but, one did crop up about a month ago. 
 Check out my threads on breakers - you might get lucky !!! 
 Cheers - Frank