Current SF Giants, Javier Lopez and Sergio Romo are scheduled to appear at the 16th Annual TRISTAR San Francisco Collectors Show on Saturday, April 14, at the Cow Palace. Also appearing are former SF Giants, Steve Carlton, Will Clark, and Frank Robinson - also on April 14. The show commences on Friday, April 13 and concludes on Sunday, April 14 - this is the same weekend as the Giants home opener.
Other sports luminaries, both past and present, are also scheduled to appear: Johnny Bench, Reggie Jackson, Pete Rose, Dwight Clark, Alex Smith, Patrick Willis, et al. TRISTAR has indicated that more players will be listed soon. At the moment, ticket prices to the show or for the autographs have not been released.
Considering that Lopez and Romo are easily accessible for autographs at the ballpark, we don't see why anyone would pay for an autograph from those guys. Some of the former players might be worthwhile to consider.