What, in borders? I'm pretty sure they're not on commission there.
Borders is a pretty meh experience though. You'll get a much better local experience going to a place downtown with a good reputation like city lights, the tattered cover or the strand. They have a lot of reasons to support them - book readings, local authors and topics, live music, staff picks, newsletters, passionate buyers, enthusiast staff.
I've never been in a Borders, but I assume that the staff are paid, that their bosses tell them to help customers, and that their bosses do this in order to increase sales.
True enough, but they do still represent a value added service. It seemed like you were saying that because it wasn't altruistic it should be left off a list of reasons to support them. Amazon doesn't discount for altruistic reasons, they do it to increase sales. But obviously you consider a discount real value no matter what the intention is.