There are 12 total treasure map items; 3 for each region of the game. In each area, you can typically purchase 2 maps from vendors, and loot 1 from a person or place. However, you DO NOT need the map in order to get the treasure item, and complete the side quest, so you can skip the maps entirely. Below you will find locations for all 12 treasure map items.
Dawnshore:
0:32 - Intimidating Feline Codpiece
1:18 - Woedica's Inheritance
2:04 - Captain Henqua's Spoils
Emerald Stair:
2:51 - Practical Pockets
3:30 - Painter's Regret
4:24 - Earthy Aegis
Shatterscarp:
5:19 - Robe of the Arcane Cheater
6:02 - Seafarer's Boots
6:57 - Dead Man's Mail
Galawain's Tusks:
7:39 - Ancient Arrowhead
8:18 - My Loyal Shield
9:13 - The Blade That Hungers
9:55 - Outro