[glchen]

Yes, there are the occasional ticket special. (I keep screenshots of the monthly specials from PSA/SGC/Beckett). Here are the monthly ticket specials for the past few years. All of these had no minimum quantity required. For bulk, as suggested, you should probably try contacting PSA directly.

March 2016
$15/ticket; no minimum
under $100 declared value
~45 business day turnaround

June 2015 - July 2015
$18/ticket; no minimum
under $500 declared value
~45 business day turnaround

March 2015
$18/ticket; no minimum
under $250 declared value
~45 business day turnaround

Nov 2014 - Dec 2014
$18/ticket; no minimum
under $250 declared value
~45 business day turnaround

July 2014
$19/ticket; no minimum
under $500 declared value
~45 business day turnaround

Feb 2014 - March 2014
$18/ticket; no minimum
under $500 declared value
~45 business day turnaround

Oct 2013 - Nov 2013
$18/ticket; no minimum
under $500 declared value
~45 business day turnaround

Apr 2013 - May 2013
$15/ticket; no minimum
under $500 declared value
~30 business day turnaround

Oct 2012
$15/ticket; no minimum
under $500 declared value
~30 business day turnaround

...

Jan 2011
$10/ticket; no minimum
1980 - present tickets only
under $500 declared value
~20 business day turnaround