Someone gave me the links for a couple of places where you can get the white umbrellas. Here's the first, and I'll see if I can find the other one and add it here too.
http://www.adorama.com/WEU45W....
This is a year or two old, so I don't know if you can still order from this page.
And here's the second one:
http://www.ckbproducts.com/60-...
