Last Home Run Hero Standing
Alex Rodriguez, Sammy Sosa, Mark McGwire, Jason Giambi (and of course, Barry Bonds)...all tied to performance-enhancing drugs. Vladimir Guerrero has been hampered with injuries and may not reach the 500 HR milestone. Looks like Ken Griffey Jr. may be the last of the old school big bats not tarnished by HOF-preventing elements, and not questionable regarding his ability to accomplish the milestone marks.
In this decade, Griffey has been overshadowed by the big names listed above, and has suffered significant slow-down in achievement due to heath issues. Now, as he makes his storied way back to Seattle, where he began his career, and he continues to add to his current 611 HR count, I would think that collectors would develop a renewed interest in his top rookie issues. You can still find his 89 UD RC for $20 or less TAC on ebay; a steal for an unmarred star like Griffey.
Griffey is #5 on the All-Time HR list, and will likely end his career at #4, behind only Ruth, Aaron and Bonds (*). Now, if we were to find out that he too juiced up during the pre-ban era, I guess we would have no choice but to put our hopes in some of these younger guys like Albert Pujols or Prince Fielder, and wait to see where they land in 10-15 years.