For what zone? Towns are generally sold in a store in that town. For areas outside of towns. Some can be bought like Castle Oztroja map from windurst npc but a lot of the maps are either quested i.e. Crawlers Nest or in a Treasure Coffer i.e. Ru'Aun Gardens and requires a coffer key generally unless your a thief and have thief tools on u to pick the lock :).