Originally Posted By: drakino
8gb Nano to 16gb Nano = $50
8gb Touch to 16gb Touch = $70
8gb Phone to 16gb Phone = $100

Marketing I guess.

The iPhone and iPod touch are different though in how they have their flash. The iPod touch has space for 2 chips on the PCB. The iPhone has space for only 1 chip on the PCB. Apple buys prestacked (like the old manual empeg RAM upgrade) chips directly from the manufacturer along with the regular single type. This is the reason why the iPhone is 1/2 the capacity of the iPod touch.

The Nano and iPhone I'd assume use the same arrangement of chips and types so there shouldn't be actually any technical reason why its an extra $50. There is a technical difference between an iPod touch and an iPhone however.