Bumping this long-dormant thread (the previous post was over four years ago) to throw in a couple of comments.
With the benefit of hindsight - specifically, Montero's career performance - I wonder if the buyer regrets paying so much for the ball. I would guess that any current value for that ball, and we're talking novelty value more than financial value, would stem from the fact that it was the very first ball thrown by a Major League pitcher to start his career.
As it happens, the day after that game, another pitcher made his MLB debut for the Mets. I have no idea what happened to that first-pitch-in-the-majors ball, but
if it was also auctioned off by MLB,
and if it went for a similar price as the Montero ball, I'd say the buyer got a
very good deal.
The pitcher's name? Jacob deGrom.
(Jacob deGrom's very first Major League pitch - a 95mph fastball to Brett Gardner for strike one. May 15, 2014, Mets v. Yankees, Citi Field. Screen capture from SNY broadcast; link to upload on Flickr.com, here).