Barnes & Noble-Crooks For Hire?

Friday night I'm picking up dinner for my girlfriend and I. I'm waiting on the takeout order to get ready so I decide to browse around B&N; for a few minutes. Instinctively, I head for the comic section and I'm checking out the newstand singles. I pick up a couple of Spider-Island tie ins, Heroes For Hire & Black Panther. They seem pretty interesting but then I see the price tag for each of them. They were both marked at $3.99 and I had no intention of paying that for a couple of tie-in books. Yesterday, I'm at an actual comic shop and I walk past the same issues again. For some reason I decide to check out the price tag and they're both priced at $2.99. What is up with that? I don't ever buy singles at the big box bookstores but is this a common practice? The covers were exactly the same except for the price tag. Can anyone shed some light on the subject?