I doubt that a used one would go anywhere near retail now. There are still some of the new ones on the car lots. A month or so back they were not really selling fast, but now are moving off the lots without discounting.
I just researched values as I got my tax notice and they taxed it at MSRP value, which I did not pay several months ago. One just sold on eBay for $17,601 with 8K on it. Another did not sell and stopped at $15,100. Edmunds is quoting around $18,000 for a used one. I would say that this range is a good figure for now. Will drop as the 06 ones become available and most folks will opt for the new 06 body style. Hope it looks beter in person than the photos I have seen.