Faerie Creative
Has medium/large LOVELY feathered wings (better than most places) and also gorgeous hand made fairy and butterfly wings and various other kinds.
 
Foxfur's Faerie Creations
right now she isn't taking any commissions, but her wings are gorgeous! go see!
 
Etoys Child's PINK Faerie Wings- cheap but cute little fairy wings :) only $7 They also have Monarch Butterfly Wings

Medium sized White and Black feather wings.
these are kinda pretty. :) they also have more costuming stuff on their main page.

http://www.bergencounty.com/a-sale.html
Feather wings in white, black and many other colors. (and other costume items) I don't particularly care for this kind of wing though, it has maribou at the top, and doesn't really look much like a real bird wing.