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The above luxury has a price. You will have to bribe someone in your local to go to the store with his phone and hack in all the shopping items and prices they have. Unfortunately it was not possible for the developers to gather this data from online stores, as there is no such database. However, regard it as a once-a-lifetime effort as prices don't change that fast, and even old prices might still give you a sense of how expensive your cooking might be. If you really need an accurate price estimation however, you will have to do it before every event. Also, if you are lazy, you can check if a local around you did the effort already and just use their prices, if you can deal with some inaccuracies, as all shops are publicly available. The ones allowed to edit the shop data are shop-admins which you can choose yourself. In case all shop-admins of a shop got killed in battle over the time and thus can't add you to the list, you can contact an alastair-admin to give you access. This prevents anyone in the system tinkering with your hard work of mapping the shopping items. Each shopping-item maps to an ingredient, and whenever an organizer uses that store, it will be shown as a possible ingredient. The more complete this database is, the better, as unmapped ingredients will make price-calculations inaccurate. The mapping mode helps you effectively mapping those ingredients.