I would say it's due to tooling costs and agreeing to buy however many sets the manufacture makes.

Tim

1951 3100 Chevrolet
1951 Chevrolet Suburban Carryall
Image
"A house is built with boards and beams. A home is built with love and dreams."
"Look deep before you leap !!!" / "Everything is Everything"
"If I say a mouse can pull a house, hitch him up"