that looks like a legit deal from a reputible seller... with a +5000 feedback score you can expect them to do good business and if not youre covered by paypal.
you can also look here and if you get an amazon card you get like $50 back.
http://www.amazon.com/gp/offer-listi...8543519&sr=8-1
they also have the tamron
http://www.amazon.com/gp/offer-listi...8543575&sr=1-1