We do not attach an additional value to an autograph and have very few autographed items. Especially since the advent of eBay, there have been many dealers who sell fake autographed items. We do not buy from such dealers and most all our autographed items were purchased from old time collectors who were known to get the autographs from stars in person. If we have any doubt about the authenticity of an autograph we will put that disclaimer in the listing. We do not give any extra value to an autographed poster unless you saw the actual poster being signed, these is no way to be 100% certain it is authentic. Autograph authentication services are very frequently wrong and I would not rely on them.