I was looking at the Pioneer Plasma's at Costco this past week as they also have a 50" unit in stock. After taking a closer look, it turns out the model was introduced in 2003. (I don't remember what the model number was, but I looked it up on Pioneer's site and the press release was dated July 2003.)
This model was selling for $4,999.00. Sounded like a good deal until I did some research. A two year old panel, even though it may be brand new, does not have the updated features that current models have. My biggest concern is burn in and pixel life. Over the past couple of years, it seems that major advances have been made in these areas.
On the other hand, the picture looked great!