Definitely second Toys for Fun and extra load outs. Extra character slots too, though this might also be BTW b/c of the extra storage/milk?
In the spirit of toys for fun - other colors of fireworks - smaller versions of the admin visual beacon - deployables of different items that act like the teddy bear.
I hope there will be some sort of transmog skill in the future so I'm all for cosmetics for items assuming players can do this with in game items w/out paying.
In the spirit of extra songs - I would like extra dances.
Assuming the game get more base emotes I've seen custom emotes in game stores before which I like.
Dyes. All of them. Especially black. People might not buy the in game dyes, but would definitely buy exclusives. But also people will be pissed if black is in there and not in game (but I'd still buy it)
Fun illusion packs that don't affect the game, but would be great for screencaps/events (i.e. different species).
Spell visuals.
Inventory folders