I did a sloppy job on this, but it's almost two am here and I wanted to get it out there. A friend came to me today and said "Wow, the new iPhone goes for about $52 dollars per ounce," so I decided to look into their pricing.
There are two ways, I think, that a typical iPhone user looks at the value of the item they stand in line for. One is in terms of weight and the second is in terms of data storage. I'm sure there are other ways, like screen size, but let's assume that's better encapsulated by the weight. The most expensive one comes in at top with a generally better value, unless you can give less than a damn about disk space.
If anyone wants to add to this, feel free to do so. I probably wouldn't turn this in for homework if I had an arithmetic class, but the idea is there at least.