????By Philip Elmer-DeWitt

????The sticker price on Apple’s (AAPL) iPhone — once an formidable barrier to widespread adoption — is falling faster than Sarah Palin’s approval ratings.

????? When it first hit the market two years ago, the 8GB iPhone cost $599.

????? Two months later, to the dismay of early adopters, it dropped to $399.

????? Last July, an iPhone 3G with 8GB sold for $199.

????? In June, with the launch if the 3GS, Apple dropped that price to $99.

????? Now AT&T (T) will sell you a refurbished 3G for $79 — which is, as Edible Apple points out, 87% off the price of the original 8GB iPhone.

????Of course, most cellphones eventually sell for $0.00, fated to become loss leaders for carriers that make their real money locking users into long-term contracts.

????Indeed, the price cuts on the iPhone have helped shift the focus from the (heavily subsidized) sticker price to the real cost of ownership: the two-year AT&T contract that starts at $74 a month for unlimited data and 200 text messages.

????At that rate, a $79 iPhone will cost you a minimum of $1,885, before taxes and surcharges.

????Refurbished iPhones, according to AT&T, “are previously owned devices that have been unused or lightly used and returned during the 30-day trial period.” They come with a 90 day warranty.

????UPDATE: Reader CdnPhoto from Toronto points out that Canada’s Fido is offering a “refreshed” 8GB iPhone 3G for $49 Canadian (about $42 US). The catch: it comes with a 3-year contract.