Not sure where I should put this. I found a Sigma APO 70-200 2.8 for sale for $600. Anyone have any experience with this lens and what do you think of the price? I'm going to email the guy to find out if it's the Sigma APO 70-200 2.8 II Ex or not. I also found a Nikon AF Nikkor ED 80-200mm f/2.8D for $650. Same questions for this lens. Thanks for any input you can provide.