But those examples are the kind of post where I expect almost everybody being prepared to pay the price of a downvote.

Those examples are so horrid that I expect those with multiple accounts to downvote with every account. No matter the price.

Also the cost of downvote should be in relation to the gain on upvote. A Plankton should be paying far less for the downvote then a wale. That is the only way this idea would work.