The decision can be tough. However, someone can be cheated as a store as well as online. I use a store when I want to compare models--touch and feel to make sure it is really what I want. I use online when it is truly cheaper and I don't need it "now!"
I've used both Adorama and PC Connection regularly and have never been disappointed in either. PC Connection has always made it easy when I ordered the wrong item or there was a problem.
I would suggest ordering through a reputable online service that you have had good comments about.