Got the service plan info I needed, item was still in stock and my new PRS-600 (black) is on it's way! The free shipping option is listed as "ground 3-5 business days" so it won't be long.
ABT customer service says the message: "We're sorry, but we're unable to offer an extended warranty to your zipcode." will appear for every zip code because they don't have a service plan available for this item.
However, Sony customer service confirmed that you can purchase an extended plan from them even if the reader was not purchased from Sony. Just call 1-877-865-7669 within 30 days of purchase, give them your serial number, where you bought it, etc.