Things you can buy in the bazaar section in shops are made of things you sold. Just sell proper items and in the bazaar section new sets will appear.
In the tables to follow I put things by their prices. If you can afford certain thing you can probably create it. The exceptions may be items that are alone in a set e.g. arrows - they will be cheaper than weaker arrows that are in a set with a bow, but you won't be able to create them yet.
In the Bazaar section often appear new items despite that you didn't sell anything. They're called "Forgotten Grimoire" and differ from one another only in the price. In fact under these names monographs are hidden - items that increase the chance that certain mobs will drop more valuable things. Each monograph is related to different class. Here they are:
Is related to:
How to unlock
Beast and avions
Appears in shop after you have defeated Thextera
Giants and bugs
Talk with weapon shop owner over 30 times
Flans and undead
Read the Notice board 20 times
Talk with magick shop owner over 25 times
Dragons and plants
Read the Notice board 400 times
Talk with armor shop owner over 15 times
Talk with any shop owner over 100 times
There's also one more item which changes the items dropped by enemies. It's Canopic Jar. Thanks to it Arcana may drop from every mob. To be able to buy it you got to sell Phobos Glaze (prize for Gil Snapper (rank III)), Horakhty's Flame (prize for Orthros (rank V)) and Deimos Clay (prize for Trickster (rank V)). It will then appear in bazaar section under the name of "Morbid Urn"