Agreed, someone who was raised steeped in revolutionary counter culture, who spent nearly a billion dollars on a campaign to be the most powerful man on earth couldn't possibly or have any Chicago crime connections to a forger, nor a dime to pay for getting a seal made.
Custom embossing seals (Just the first of many LiveSearch hits)....
The seal is not difficult like you say. What is difficult is hiding its procurement and use by an organization like Annenberg. They are not simply going to photograph and publish the piece of paper that came in the mail some someone unless they know who that is. If that someone is Obama or an aide, then that aide has to procure and use the seal. Your own search for one was just recorded.
Did they guy who made it get paid for his silence? Did they go through the records office to get one? Maybe someone from the records office took one home one day and then sold it on the street? If so, it still has to find its way into that Obama aide's hands. There are too many pieces of the puzzle missing (or that would have to be silenced).
All the more reason to spend a few grand gumming up the potential opposition for 2010. What better way than to marginalize them and distract them with a few trivial forgeries like fight the smears, while making it obvious to the rest of the world that the real docs are real (factcheck). It is far cheaper to keep the opposition fractured and fringed than to attack them head on.