Based on what economy? In the US alone, with only 50 states, there's probably thousands of different economical variations.
A couch in North Georgia would most likely have a different cost than in mid or south Georgia, and even more different on the east coast and west border. [;)]

@hawk : [Moderated]

It is not necessary to generalize a price for an object.
It is not a database that I wish but a price of an object in a project that will certainly differ (or not) in another project.

I repeat I speak of project, not a price memorized to an object ...

I hope (for everybody) that it's clearer.

[:)]