I was looking for info for a friend, which is how I found your post and thought I'd share with you the great website that I found.
I think if you bought the stamp you can't create something with it and photocopy it or put a copyright on it. The image on the stamp is already copyrighted by the company/artist that created it. Stamp companies have policies on use of their stamps for creating and selling things, even the specifics of where they will allow you to sell and quantities and such.
Check out this link:http://www.littlebit.com/angelList/angellistcomplete.htm
Very helpful. Judith Perry was very thorough. Thanks Judy!
Good luck to you WitchCat!