I would bet that the Short Line sign will go for the most $, and well above what I could bid. Ebay user "fbe3" has bought quite a few of the RMC and AMC signs in the past and paid $415 for last year's Castle Ravine trail sign, $418 in 2008 for the King Ravine trail sign, and $611 in 2009 for AMC's Pine Link trail sign. I'd bet that this person will be bidding for the Short Line sign.
Hope the RMC raises lots of money to help maintain the trails!