Since the price fields are not available to us mortals (non true admins) the vast majority of the decks don't have any of this information. I also would question if it has any real value or purpose. An individual might want to know at the collection entry level what they paid for their own deck, but at a database entry level I'm not sure what good that is. Prices often vary depending on where you live and if shipping is included (hidden) or separate, how many decks you buy at a time, prices vary over time and then there is the aftermarket. Not to mention exchange rates vary over time so if including multiple currency options should those reflect current exchange rate or just list price at the time.
My suggestion would be to remove that field from the database collection entries, or if it is kept then provide guidance on how to use and keep it open.
Certainly though, whether it is kept or removed at the database level, having this option at the collection level might be a good suggestion.