It is quite rare that you’ll be taking over the #1 spot of any product on Amazon anytime soon. For that reason we would recommend that you track at least five different positions of any product that your interested in, and not #1.
For example, if you are interested in tracking “Rechargeable Bike Lights”, track two or three results on page one and then a couple on page two. We also recommend that you track some with varying levels of reviews. We always like to see the sales numbers of listings with low levels of reviews because that’s where we will be starting ourselves.