You could get a iPhone 3G for $100-150, and then sell THAT when iphone 5 comes out. I expect iphone 4 prices to drop significantly after launch but iphone 2g and 3g should not change that much.
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That's only for Verizon.
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even if it does fail today I would pick one of these up till iPhone 5 is released
http://www.newegg.com/Product/Product.aspx?Item=N82E16875101038
That's only for Verizon.