How valuable are "milestone" GU balls?

[Sulross]

I recently bought a GU ball where the player (Beltre) passed Mickey Mantle in RBIs. He was still relatively low on the list but he still passed the Mick in a major category. Any idea how much more a ball like this is worth than a run-of-the-mill hit/RBI ball by the same player?

[carbonrosa]

As always, a game used item is only worth what someone is willing to pay. That being said, how much more is it worth is up to interpretation. There is some value added to that ball since it is a milestone but someone like me who buys a lot of baseballs wouldn't look to pay much more for it especially when there could be more milestone hits to collect. Baseball collecting looks to be at the bottom when compared to bats, jerseys and fielding gloves. Those three tend to fetch a a higher premium for stars. MLB auctions is a bad indicator for determining the value of any item. Auctions like that tend to bring the worst out of people who don't know when to quit and baseballs in particular sell higher then most are worth with the exception of true milestones and rare hits. The only way to determine it's value is to see what other RBI hit baseballs from Beltre have sold for in the past through auction sites and ebay minus MLB auctions. It's also good to watch the game on MLB tv to see if that ball is attached to any other player by following it in reverse. I bought an Albert Pujols RBI Single the other day that while watching the ball in reverse showed it was attached to a trout single which was attached to a Calhoun walk.