The phrase "prices publishers" means setting or determining the cost at which publishers sell their products, such as books or magazines. Full definition
Under agency pricing publishers set the price for their titles and, guess what, it is the same price everywhere. (madgeniusclub.com)
Nobody expects them to be free all the time or priced at less than # 1 but equally, there's no excuse for the high prices some publishers seem to want. (selfpublishingteam.com)
Which would mean the coupon definitely couldn't be used on agency pricing publishers there. (antipope.org)