Nikon'ers: I currently own a Nikkor 28-70 f/3.3-4.5 and Sigma 70-300 f/4-5.6D DL (not the APO version). I'm looking to sell these lenses (I'm hoping to upgrade to faster lenses). Can someone suggest what prices I should expect to sell these two lenses for ? Both lenses are in mint/pristine condition, and come with all instructions/box/original caps, and have been exceptionally well maintained. Thanks, in advance. Cande Ananth