I have 90 mesh bags, size 20"x30" (50lbs) in brand new condition. I’m selling them for 50 cents a bag, which comes out to 45$ for the lot (I bought them for 1$/bag).
I live in London, so if you come to the conference it’s a short drive to pick them up from the venue.
(Sorry about the crappy photo, this is a used one that I’m keeping.)