Yup. Simple...do this:
Grab about a "boxful" and call it Box #1.
Take a pic of the pile.
Use a kitchen scale or bathroom scale and give the weight.
Give the price.
SOLD!
When you're clearing like that, you don't need a pic of each and every single fabric you're offering. But if someone can peek at the pile, you'll be alright. And folks that need to be more choosy? Well, maybe this isn't the sale for them.