The link that you posted is an excellent comparison BUT no evidence that "$30" is the right price point for a good charger. The iPhone charger has poor rating on current sag. The ipad charger has poor rating on voltage sag.
Actually, the Apple chargers in that link displayed the expected behavior for the USB 2.0 "extended power" (can't think of the actual title) specification. The author has a fancy oscilloscope, but that doesn't mean he/she knows everything.
I'm not the one making the claim that $30 is "overpriced". You are.