For current month (April, 2020) Quest Master offer XP Booster for 400 QP, Costume Gift for 1500 QP and Animal Crossing… wait, The Secretary skin for 1000 QP.
The Quest costume is changes every month. But you can increase cost to 1200 QP, but you with Quest Costume player also will get avatar and hub title (like all marketplace costumes). Like:
Rubber Ducky (1200 QP):
Rubber Duck Avatar
Quack-quack-QUACK! hub title
Gingerbread (1199 QP):
Christmas Bread avatar
Merry breadmas! hub title
Winter Ferret (1200 QP):
Cute Ferret avatar
The Unfrozen hub title
Toxic (1200 QP):
Dangerous water avatar
The Toxic hub title
Neon Tiger (1200 QP):
Neon Tiger avatar
The Neon RAWR! hub title
The Secretary:
Rich Dog avatar
I am Secretary. hub title