While at the beginning they will have very limited amounts of items, they will increase their item pool as the Hunter traverses the world, defeating bosses, entering new areas, acquiring Badges, unlocking Chalice Dungeons, and more.
There are two types of Bath Messengers, which are differentiated by the currency used to acquire items: Blood Echoes shop and Insight shop.
Has the most variety of items overall and allows purchase of the more common consumables and materials in-game. Is also the way to purchase Weapons and Attire (unlocked by acquiring Badges). The Bath is initially populated by only one Messenger, but as players find Badges, the Messengers will grow in number, up to eleven.
There is also a variant of this Bath that can be found in the Chalice Dungeons, selling the “Sinister” variants of certain Chalices and the uncanny/lost variants of weapons from the DLC.
The Insight Bath Messengers reveal themselves when the player has gotten their first Insight point. This one has less variety, but offers very rare consumables and ritual materials (when players start delving into the Chalice Dungeons). It also allows the purchase of special attire (unlocked by killing certain bosses). Has 4 Messengers at all times.