Upload & Sell: On
As mentioned above, exact matching is very hard, especially under different light sources, which produce metamerism (different color emanating under different light for certain fabrics and pigments).
As a side note, I recently purchased a used 100-400L, and it came without a hood. No problem, I turned to my trusty eBay and the Chinese sources that sell the uWinka brand replacement lens hoods. They offer one in "white" (the recent Canon light "putty" color), and for my purposes is "close enough". I also ordered a black uWinka from another seller, but haven't received it yet. Price of the white with free shipping was around $14, and the black was a few dollars less. It's not exactly the same quality as the much more expensive Canon genuine hood, but "close enough".
Here are some shots under different lighting -- well, same lighting (soft overcast) but different surrounding surface colors creating different colored bounce lighting.