Brain Stew

Once upon a time, a man goes to a restaurant to eat dinner. On the menu he sees various kinds of brain stew. The lamb brain stew is $20, the fish brain stew is $25, the chicken brain stew is $15, the cow brain stew is $30 and so on, at the bottom he sees blonde brain stew and that is $999. Curious, the man calls the waiter and asks him, "I see the brain stew is reasonable for different animals, but why is the blonde brain stew so expensive?" The waiter replies, "Sir, we rarely find blonde brains, that is why it is so expensive"