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.  

DC Comics Presents #1, signed by hand by legendary comics artist Jose Luis Garcia Lopez and authenticated by CGC with a grade of 9.6.  Features the 4th Superman/Flash race and a Professor Zoom cameo.  With Signature Series books a certified CGC witness actually observes the signing of the comic so there is no possibility of the real autograph being switched out with another.  As of this writing, there are only 23 SS copies of this book graded, five grade higher at 9.8 with only four others at 9.6.  According to GPA, the only recorded sales of 9.6 was at $320.