Even AT&T must have expected that it would have trouble burning through iPhone 3G inventory once the 3GS was released. After all, it doesn’t take a rocket scientist to figure out that a $100 difference in up front cost should be the least of the deciding factors when considering an iPhone — or any smartphone for that matter. Ok $100 might not do it, so AT&T tested the waters back in June with a $120 differential where refurbished 3G units were concerned. Apparently not many people bit because the carrier has decided to shave another $30 off the price of refurbished phones, bringing the 8GB refurb to $49 and the 16GB refurb to $99. So people, the bottom line is if you have $1,680+ to spend on your cell phone service over the next two years (or $960+ on a family plan) but that extra $30 on the handset price was scaring you away… Happy birthday. As far as we’re concerned, the difference between the 3G and the 3GS is well worth $150 up front.