I bought one the other day for 350 shipped. I thought I was getting a smoking deal but not really. There is the Shadow and the ultimate shadow. The Ultimate shadow sells new for around 650. The shadow sold for around 399 new. The biggest difference in the two are the bottom metal. Since yours doesn't have that, it means it was a shadow that sold new for 399. It's probably still worth that in my opinion because you can't go buy a new one for that anymore. 350 to 400 is my guess.
Here's a couple of pics of mine.
