http://www.silkscreeningsupplies.com...34/page/826321
The finest this company has is 110, and it is cheap. It will do if you are doing any screening for kief. Not much dif. between 110 and 100. I took fabric arts in college and am a screen printer, as well as many other hats I wear!
But I would try out Pappy's idea first. It would be cheaper if you just need a small amount.
Peace.