1. Checkbox in options to sort by *** (default)
2. Sort by rarity
3. Exclude owned items (pets, mounts, emotes; would've like armor/weapons as well with short tooltip about legacy availability i.e. unlocked, unlocked on another char)
People would say you thanks dozens times.
Have a nice day.
UPD: will appreciate some sort of pop up icon while browsing collections near gtn "Search on market".