Regarding the comics industry recent reholder scandal / scam, please note that all books I sell were submitted directly by me to CGC at various comic conventions (as well as the occasional private signing event).  I do not buy already graded books and then resell them.  So every CGC item I have for sale was graded by CGC and then came directly to me and not through another dealer.  Please further note that photos, prints, and original art sketches (that are not on actual comic books but are rather just on sketch paper or the like? i.e. anything certified by CGC that does not have a grade, are not searchable on their site by the serial number.  Only graded comics and magazines - items with grades - are searchable by serial number.  However, for such items not searchable on their site, you can call CGC Customer Service and they can verify the item authentication over the phone.  

Signed by hand by both Amanda Conner and Jimmy Palmiotti and signed and sketched by Rick Burchett, this blank sketch variant cover to Harley Quinn #0 is professionally graded by CGC and is part of their special Signature Series.  With Signature Series books, a certified witness actually observes the signing/sketch of the book and then immediately takes possession of the comic so there is no chance for the real autograph/sketch being replaced or substituted.  CGC case is scratch and defect free and will be shipped with the utmost care.