It's a healthy dash of guilt by association; these iSuppli reports unfortunately lend themselves to sloppy reporting. This article is a typically wonderful specimen, which crosses lines freely with nonsense sentences like these:

"On the high-end Wi-Fi model, which offers you 64GB of space for $699, Apple’s non-manufacturing profit margin shoots up to 48 percent."

As though you get to handwave away non-manufacturing costs and then call it a "non-manufacturing profit margin."