Apple is currently offering special limited time pricing on its stock of Certified Refurbished fourth-generation iPod nano units. All 8GB models are now $99, down from the normal price of $129, while the 16GB models are now $149, down from $169; both prices represent a savings of $50 off the retail price of new units. All Apple Certified Refurbished iPods include Apple’s one-year warranty, and are typically limited to the number of units on…