My 1978 lorry is covered through SEIB and we have the extra breakdown recovery - NFU wouldn't insure her at all - so although I am paying more than absolutely necessary for the insurance at least i know she is fully covered!
Another thing to check when you are insuring is whether you are coverd if you get a prohibition order on your lorry. Mine was picked up from the MOT station (twice) and it would have been expensive if the insurance hadn't covered it.
My 26 year old Bedford is covered by British Equestrian insurance Brokers for breakdown recovery. About £160.00 per year which includes recovery of horses.