[Lucid:]

Are you asking about both DIs and Event Items? Either way, the basic answer is yes, you will have to buy one to wear each pose.

for event items, the items usually come in "bundles" so they unpack into multiple items so you can wear the whole set at once as soon as you buy it. however, buying the items from users, you will have to be sure to buy every item from the bundle.

for DIs, you may end up having to buy multiples to wear certain poses together, but we do try to include as many of the anticipated commonly-used combined poses as we can fit.