Mariano Autographed the Yankee Stadium Bullpen Phone
The final call.
The Yankee Stadium bullpen phone was apparently replaced during the offseason, since last year's showed up at Steiner Sports, signed by Mariano Rivera himself. It reads:
"My final call to the mound on 9/26/13. 652 saves."
I can't imagine how much this would go for at auction. Maybe as much as this?