I did three of their Jackson-Sharpe passenger car conversions for a pal to take back to US with him. At around £300 for the conversion kit, plus £250 for the car, and about fifty hours careful and painstaking effort on my part, they were never going to be a money-spinner for RG.
They looked nice, but..............................Holeeeeeeeeeeeee etc.
Life was too short for me to do any more, and he took them, and three kits, back stateside when he left.