Tassles are really easy to make, here's a link:
Tailoring an off-the-shelf-costume
I found this link for the hair falls:
Belly Dance Tips: Cowrie hair falls for tribal belly dancing
I just googled "tribal hair falls" and got several links.
For harem pants, try Juliari Designs:
harempants
I see many colors of slit harem pants, but not black, or any paillettes, but there is a pair of plain black chiffon harems. You could always put in a slit, that would be pretty easy to do or have someone do for you.
You could also contact them to see what else they have in stock. I know the owners of this business and they are great folks.They are having a big sale tomorrow that I hope to go to and they have just brought back a bunch of tribal stuff. You should contact them and ask! Their email is
ariana@efn.org
Good luck with your costume.
A good resource is the DIY/Belly Dance on a Budget Tribe on tribe.net. Check it out:
DIY/ Bellydance on a Budget - tribe.net