Not worth the bits it's encoded in
Given the amount of price spamming in the results for google shopping (froogle) results, I don't think that this will be a very robust number.
I have almost given up on using it because of the number of made-up retailers that all point to a few retailers who don't sell for anything like the price that google says they do. In addition, there are a lot of results that quote prices before tax and other necessary add-ons (not even carriage) that skew the results.