rb,
  Shouldn't be any VAT, customs costs ast we are all one big happy Euromarket now.  
 Maybe needs to be de reg'd in Germany before re reg in UK? 
 try the DVLA @ 
www.dvla.gov.uk  I have a reasonable idea what stuff needs to be done when a car comes from Japan but thats no help to you at all!! 
 It must be well worth it if you are thinking of going to the trouble of buying a bike from Germany.  
 I know someone who brought a monster back from germany but they were OHMS. They can't usually remember what happened last week never mind a few years ago!! 
 Ray   
 Ray.