Hello!
If you are in Canada at all, I work at a shop that can ship bald caps and all the required make-up to go with them. Check us out at www.donshobbyshop.ca. If you are however outside of Canada you will have to do some searching for local companies that carry the products. The best idea is to search the brands online and see what stores sell them. Decent brands you can go with are Woochie or Don Post. I would recommend Woochie over Don Post personally. I found one website that has a good list of distributors in many countries depending on where you live. This might be a good place to start looking for the closest distributor to where you are. Woochie latex bald cap link: http://shop.cinemasecrets.com/woochie/l ... tural.html
Or you can try Amazon: http://www.amazon.com/Cinema-Secrets-Wo ... _pr_sims_t
(not sure how Amazon compares to an actual cosmetic website)
^ I have not ordered from either of these places, so I cannot say for sure how good they are. Just a few links recommended from others.
Woochie also makes different coloured bald caps, including White, which is great for Asajj.
If you need any advice or have any questions on putting a bald cap on, don't hesitate to ask. I've done a few myself and sell the products everyday so I can give you my personal opinion on what I think works best (others opinions differ and there is no one right way to do a bald cap). There are also quite a few good resources online for doing bald caps as well.
You are of course in a great place for advice on Asajj ~.^ As I'm sure there are a few here who have done the bald cap thing.
Good luck on your costume!
Cheers,
Nef