It’s pretty well accepted that one way to gauge something’s value is to see how it retains said value. One example would be, say, a BMW vs. a Ford Expedition: You can get into either one for around $35K, but after a year what will they be worth?

The same goes for the mobile device market. I just sold my iPhone 3GS on eBay for $300–in four minutes. The interesting part is that’s how much I paid for my iPhone 4, and this is the third time in a row that I’ve done the exact same thing.

In other words, since camping for my first iPhone I’ve either broke even or made money selling my previous one–even though it was a used, previous-year model. That’s extraordinary.

So my point is simple: we have another data point in the quality/demand debate between iPhone and Android: their re-sale values. Let’s check some rough numbers on a top-google-hit-site that buys used phones: cellforcash.com

Android Phones

iPhones

Granted, this is just one site I picked from the top of Google, but I am willing to bet it’s representative. And look at the numbers: the top Android phones that just came out aren’t even worth what last year’s (or the previous year’s) iPhone.

DROID Incredible: $69

EVO 4G: $81

The absolute latest models, mind you. And the iPhone?

iPhone 3: $114

That’s not even the 3GS–that’s two generations back, and still more than the EVO 4G. Last year’s model (the 3GS) goes for $240–almost 3x Sprint’s iPhone killer that came out like 20 minutes ago.

Yeah, pretty compelling… ::