This Star Player Cobb card has been on ebay for a while with the following description: "The last SGC 10 (1) sold for $6900 and this card rarely comes up for auction." The seller generously listed it for a huge discount at $5299. Only one problem: the "last" SGC 10 of this card was his purchase 30 days ago for $2629. The $6900 figure is from a sale in 2008.
http://www.ebay.com/itm/1928-Star-Pl...item20d161bb63