how do I go about pricing items for selling? the broker doesn't have all the items and I think some of the default prices are kinda low...

You can always check what similar items cost, and what they sell for. For example, if you were to sell a Regular Ny'vene Essence, you could check what a different Regular Fabled Essence is up for, or if you try selling a pre-coloured outfit you can check what other pre-colours of the same type sell for, etc.

If there's nothing comparable, I usually just price it on the high end of what I would ideally like to get for it, and if it doesn't sell just lower the price over time.

Maybe I can help if you share what item you're talking about?

I've got pretty much a whole tab full

arctic nomad's garb (sunrise)
silver werewolf costume
woodsman's outfit (I already had this somehow????)
cloud hopper's horns (Long - Regal)
gelidan monarch's champion (champ)
angelfish shell staff (koi)
ferikki tamer's bouquet (polar)
forest witch's grackle (lovely)
garden tender's hanging plant (duskvine)
marionette's sewing needle (hallowed)
floating candles (green)
viking marauder's companion (wulfgar)
gingerbread rolling pin (frosty frosting)
mushroom fairy's friends (galaxy)
lupora tamer's hat (spiked - timber)
tundra nomad's ears (squirrel)
sylesti egg basket (spring)
ghostly pirate cutlass (sea algae)
thicket wanderer's shillelagh (withered)
nightmare lord's flail (trick-or-treat)
winter mage's crown (short - conch shell)
angelfish seahorse (koi)
steampunk pumpkinachine (copper)
jackalope outfit (cream)
steampunk pumpkinachine (ruby gold)
jackalope horns (gray)
demon channeler's sickle sword (felfire)
ancient mummy's scepter (elder)
pet bat (batty)

if this is too much for you, I'll definitey do some once I get my party figured out

Oh that's definitely a bunch xD; Honestly I can suggest you what I've seen people do, take a screenshot of the items and post it on the item sale forum and get offers. Ender has a great example :D A lot of these are older items that people can't expect to be regularily put up on the broker, so if they're looking for something particular that is from past fests they're more likely to check the item forum (I would guess, I've done it before but not sure how often people look).

ok! thanks for the idea ^w^

although, one item I want a definitive price on is a "qitari costume: father winter's helper" and the same but with zolnixi

Tricky, it would be 1mil if we go by the usual 1:2000 diamonds rate. But on the other hand usually on the exchange you can get diamonds for less, so I would start at maximum 925k?

During summer it will probably be tricky to sell it for that price, I would guess you have a better chance during the colder months :D