I was looking for a fur windscreen for the built in mic in the XF100 and B&H has one but over $40, which is ridiculous for just a small windscreen, but they have this one too:

K-Tek KR-40-60 Fur Windsock for Canon XM1, XM2, GL1 KR-40-60 B&H


However, I'm not familiar with the Canons XM1, XM2, GL1 and GL2. Would a fur made for these fit fine in the XF100? If not, what others can you recommend for about $20?

This works great. It is $4.99 more than what you wanted to spend.......:)

Rode Dead Kitten Artificial Fur Wind Shield DEAD KITTEN B&H

Actually I had seen that one, but I find it in really bad taste for them to name it "dead kitten".

I found the solution at home since I had bought a fur for my Sony AX2000 which was actually made for the Panasonic HMC150 but fit very narrowly in the AX2000. Since I will be selling the AX2000 and the built in mic in it is a piece of crap that can barely be called a microphone anyway, I carefully removed the elastic from the fur and now it fits almost custom made for the XF100 :)

Obviously this is removing the holder for the external microphone, which might be a problem in some occasions, such as being in an event where at times you need a directional mono microphone and at times you need a stereo one.

"Dead Cat" and "Dead Kitten" are terms used in the business for years....even if in "bad taste".