I love this idea and your collection so far. Suggestions/ideas below which is a long list, but would keep you busy:

- Skirts in different styles
- Shorts/Pants
- Boots of different heights/colors. I'd start with basic colors black/brown/white
- Flat shoes in various colors
- Wings
- Capes
- Earmuffs
- Scarves
- Bracelets
- Necklaces (Gold/Silver/Black/etc.) Different links i.e. chokers/long (down to where a belt would start)/one which would fit in a v-neck shirt.
- Ribbons for hair
- Hairstyles is big. Offer in variety of shades (Basics blonde/brunette/black/red/orange/gray) (Colored Pink/Teal/Green)
- Hats would be very popular.
- Masks would be fun for diff occassions.