Ballroombelle,
There are literally tons of suppliers of fabric and notions out there. And I think I've searched them all with my theater work.
Try a good search engine (I personally like Google) and go to the advanced search function. In the search protocol type in both notions and ribbon.
If you type in just notions you'll get everything from buttons to zippers (ok, I couldn't think of an "a" notion off the top of my head!) and just ribbon will get you non fabric ribbon.
The tricky part in the results will be to sort out the sites that sell to the industry. Not sure how much you're looking for but sometimes the wholesalers will work with an individual if you're buying in large quantities. I have been able to do this when I need full bolts or rolls of fabric for multiple costumes.
Deb