Local prices from scanned barcodes require Location Services to be active to produce latitude and longitude. Location Services can be run on an iPhone, iPod Touch and an iPad. To make sure that Location Services are running
1) Run the Settings app and click on General->Location Services
2) If the Shopping List app is not listed on the Location Services page, this could be because when the app has been started and when the app has asked if the app can "...use the Current Location" the user has enter "NO" more than 2 times.
3) To fix the problem in 2), in the Settings app, from the beginning select General, and then at the bottom of the General page select "Reset" and then at the bottom of the Reset page select "Reset Location Warnings".
4) Now when the Shopping List app asks if the app can "...use the Current Location" select "YES".