Item 360337583253, the 6C 2300 manual (in Italian), sold for US $1,781.98.
Item 360337578585, the 6C 1750 manual (in Italian), sold for US $2,490.00.
If you think that's expensive, consider this:
Item 360337573597, Ferrari 275 GTS / GTB pouch and work shop manuals, sold for US $9,934.00.
Item 360338129136, a 6C 2500 owners manual from 1939 offered by the same seller of all three manuals above, is currently at US $511.00 with almost 2 days left. It appears the higher bids on all items seem to come from 2 bidders only.