It won't be a dusty refurbished heap of junk either. SK Telink somehow got its hands on pristine, untouched 2009 iPhones in their original packaging, and it will resell them in original condition after ensuring that each phone works.
Even though the iPhone 3GS will be sold as "brand new," don't expect it to work the same as a recently released iPhone. The iPhone 3GS was discontinued back in 2012, and it only runs iOS 6. As a result, many apps (and even iMessages) won't work on the phone.