iPad mini price formula, I fuond; $40 x screen size, and for Retina $50 x screen size

from article by AppBank

I found simple iPad series price calculation formula that I had never seen in internet.
That covers iPod touch as somebody said as "iPad mini is large iPod touch."

• non Retina iPad's price is $40 multiplied by display size in inch.
  For Retina model, $50 multiplied by display size.
• Above is for 16GB model. For 32GB and 64GB, each time when doubling the memory, plus $100.
• With Cellular, plus $130

That's all.
Let me verify it using table.

		iPod touch 5gen	iPad mini	iPad 2	iPad 4gen
display size		4	7.9	9.7	9.7
16GB	multiplied by $40		329	399
	Retina; multiplied by $50	199 (not available)			499
	with Cellular; plus $130		459	529	629
32GB; plus $100	multiplied by $40		429
	Retina; multiplied by $50	299			599
	with Cellular; plus $130		559		729
64GB; plus $200	multiplied by $40		529
	Retina; multiplied by $50	399			699
	with Cellular; plus $130		659		829

In this table, I wrote real price.
But gaps between calculation are smaller than 4%.
Now let me simulate several predicts for iPad mini.

• If iPad mini had 7 inchi display similar to other tables, the price was $40*7=$280. I think it is not competitive nor innovative.
• If iPad mini was with 8GB, the price was $329-$100=$229. I could be $199, same as Nexus 7 at that time, but they lowered soon.
• If iPad mini with Retina display wil be released, the price will be $50*7.9=$395~$399. At the time it will be released, iPad 2 in that price will be retired, and iPad mini should be major member in iPad series.

How do you think this?
I'm looking forward to half and/or one year later.
[Japanese version of this post]