Sable

I'm still adding to this list, but here is what I've come across so far. If you've found others please comment and I'll add them to the list and credit you.
I would advise not to buy any clothing items until later in the game. Cuts (money) doesn't come quickly in this game and maps/badges are more important to buy at first.
The best way to make a couple grand quick is to farm Lighting Crystals at Crystal Plateau in the SW corner of the map. Grab the quest Lighting in a Bottle from the Machinist Zahra at Seven Sisters Station in the SW region first. I'm unsure if these crystals grow back over time but they sell for 100 cuts a piece. Make sure to keep 3 for the quest.

Bouldering Top - The Wind Tower, in a chest on an outer tower.
Bouldering Trousers - In a chest next to the mask at the top of the Bridge of the Betrayed

Monumental Stone Top - Solve the statue puzzle in the same area as the cartographer's balloon in Redsee (NW area)
Monumental Stone Bottoms - Bridge of the Betrayed, stand on the pedastal facing the large mask statue at sunrise when the shadows of the swords cross.

Eyries Top - 1 grid square East of the cartographers baloon that's SE of Bridge of the Betrayed. It's in a chest in the structure to the SE
Eyries Trousers - 1 grid square East of the cartographers baloon that's SE of
Bridge of the Betrayed. It's in a chest in the structure to the N

Biker Top - Buy from Bike Merchant Ahvid at Eccria
Biker Trousers - Buy from Bike Merchant Ahvid at Eccria

Eccrine Guard Top - Hidden water passage at the bottom of Thieving Magpie Well
Eccrine Guard Trousers - In the sewers of Eccria

Sand Surfer Top - Buy from Merchant Habat at Five Bells Camp 2 squares W and 1 square N of Eccria
Sand Surfer Shorts - Buy from Merchant Habat at Five Bells Camp 2 squares W and 1 square N of Eccria

Eccrine Top - Buy from Fabric Seller Kalia in Eccria
Eccrine Trousers - Buy from Fabric Seller Kalia in Eccria

Beetle Station Top - Buy from Fabric Seller Kalia in Eccria
Beetle Station Trousers - Buy from Fabric Seller Kalia in Eccria

Hakoan Top - Buy from Hakoan Merchant Caimin at the Crystal Plateau in southern Hakoa
Hakoan Trousers - Buy from Hakoan Merchant Caimin at the Crystal Plateau in southern Hakoa

Machinist Trousers - Solve The Watch puzzle in The Wash region (SE area of map)

Whale Ship Mask
Whale Ship Trousers
Whale Ship Top - These are granted as a set for solving the puzzles at enough ships that Sarin grants you access to a room on the massive Whale ship in southern Redsee region.