A gypsy or belly dancer costume is easy to put together with clothes you might already have. A full skirt or two, a peasant blouse or fitted plain teeshirt, clipped up to make it a midriff baring shirt for a belly dancer, lots of shawls and scarves in bright colors all look like the movie versions of gypsies and bellydancers.
The right accessories finish off the look.
A wire and chain necklace with fake coins hanging off of it looks very sparkly and works well for this sort of costume.

Thishandflower works up fast in netting and looks very pretty and mysterious.

Coin earrings are a nice chunky and contemporary look that are very wearable after Halloween.
Big dangly brick stitched earrings also work well for this look. This pair done with asymmetrical fringe was one of my mom's favorite patterns. In this example I used tiny clapperless bells that chime as you move your head.
Of course, you can't forget bangle bracelets with this costume. This project is an old favorite of mine, they work up really fast and are a great use for extra beads or bead grab bags. You can also use smaller beads to make smaller rings to use as scarf clips or with much finer wire and beads, nice hoop earrings.