I was pointed over here after posting about having bought a reader from the Sears website. After poking around a bit, I called the catalogue order# and asked the rep if they had an item# or any other info on which model it was, and she said it was a PRS300. I pointed out the discrepencies on the website that make it look as though they're selling a 505 model (and it's listed the same way in the Wishbook that came out recently, too). She said she'd pass the info along to customer service to make any necessary corrections.
Mine should arrive around Wed-Thurs next week, so I guess we'll both see