How does an autographs price change if it is personalized?

i'm not sure if it would go down, bcuz if it is personalized, you know for sure that the star actually has touched it rather than have it have been a print out. if someone sold like a daniel radcliffe, david archuleta or taylor lautner autograph, and it was personalized, i'd get it even with a random name cuz it like wud have been from them really. hehe but i got taylor's autograph whn i met him :)