The last one I can find was in the area of $500 about 8 years ago and it wasn't exactly the same. I priced new ones to get an idea and currently if you can get one for under $2100 I would be impressed. Rebuilding isn't much cheaper, if at all, when you take into consideration core cost, parts, shipping, labor, etc.
So, this is how I came up with my number. All this being said, I know it is a good working unit, and I will entertain offers.