fyi in treasures there is no goodies, just a trash
sometimes you can find malachite shard there, and set items costs max 5k gold but only if you loot treasures when you are max level - vr16
when you find or buy treasure map and open it - you will figure out why you need addon for it
or you can look at the 4th and 5th screenshots of the Lost Treasure addon page to see how treasure maps looks like
regular price for treasure map is like 100-500 gold at the guild stores
except Cyrodiil maps - like 3k, and Orsinium maps, high price too