Towbar prices "Up North"

Hi Folks, just bought my first motorhome and I need a towbar so I can fit my motorcycle rack. Why are tow bar prices so varied, nearly double in some cases. Due to legislation I can,t  make my own so I have to have one made by the trade. The only one I could find under £400 was in Lancashire, a 350 mile round trip from my home in Northumberland. It would cost less than £100 to make one up. Has anyone else had similar problems and could recommend a reasonable towbar fitter in the north east.

                                         Cheers,   Jim.