Most trailer places will make those for you - they are normally called a motorbike trailer.
I had my trailer made up by Rutherford Trailers (Craig is the guy that runs it) and they did a great job and good after sales support too. Other places around are Terrace Trailers and Port Stephens Trailers up at Raymond Terrace, and also a new place also at Rutherford called Hunter Trailers. There is a place at Cardiff called TRG Trailers but i think they are just an agent for one of the other places.
