Coming in very late to this discussion, but I'm very supportive of this type of policy.

For the objections that are being raised in terms of applying this method to a piece of original comic art, consider that if you sell such an item on eBay, you're paying fees to eBay for this service. If you sell it through any number of auction sites like Heritage, the buyer pays a seller's premium to the auction house. These are costs of doing business for the services these sites provide that facilitate the selling the artwork.

An additional fee that could go back to the creator or his heirs -- call it the creator's premium -- ultimately becomes just another cost of business.

Enforcement would come through the creation of a registry that would tag and track these items to ensure their provinance, and would also facilitate the calculation of tax on the transaction (i.e. final sale price less original acquisition price).

International enforcement would be a matter of instituting this as a component of the World Trade Organization intellectual property agreements. 

And for those who try to dismiss this approach using the house builder example, you neglect to consider that homes are a mass production item as opposed to one-of-a-kind originals. Nevertheless, I could see a scenario where the architect / engineer could receive a similar ongoing compensation for the profits accrued from the re-sale of their efforts.