Price Transparency

I wonder if such a collaborative online ” Price Book ” , as mentionned here :

furthering transparency about prices according to location , and through time , per equivalent product ,

could be interesting ?

Or do you already know such kind of Price Book ?

It could be interesting to empower consumers vis a vis shops , but also vis a vis politicians , …

When googling , I find Do It Your Self ( DIY ) style recommendations such as

but not yet any collaborative project of gathering and comparing information , combined with a google maps api … ( or google earth kml )