Connor, apparently, likes to change clothes a lot. In Assassin’s Creed 3 fact, it will be possible to buy 6 different clothes in stores and collect 5 more after completing some side quests.
Remember that the clothes have a purely aesthetic function, (it will be nice to see them on the mannequins of the seal) do not offer any kind of armor or increase to the normal resistance of Connor.
Below you will find the complete list of clothes with their purchase price and unlocking conditions.
KILLER'S OUTFIT - initial equipment
BOSTON OUTFIT - £500 - sequence 6
JAMESTOWN OUTFIT - £1500 - sequence 6
CHARLESTON'S Gown - £3000 - sequeanza 6
NEW YORK OUTFIT - £1000 - sequence 9
PHILADELPHIA OUTFIT - £2000 - sequence 9
BALTIMORA Gown - £2500 - sequence 9
These clothes can all be purchased in the various emporiums that you will meet, they are nothing more than variations of origianal dress, so it is normal not to see them worn by the mannequins of the estate.
ALTAIR OUTFIT - Unlocks after completing all main missions, including secondary objectives
CAPTAIN KIDD'S OUTFIT - Unlocks after completing the nautical location Oak Island
ORIGINAL ACHILLES' DRESSES - Unlocked after completing the mission The painting of Achilles
KANIEN'KEHA':KA'S Dresses - Unlock after collecting all Feathers
EZIO'S OUTFIT - You can only buy it at Uplay
These outfits, once unlocked, are stored on the Estate's mannequins.