Just wanted to follow up and add a point to get people thinking about what quantity they might want.
Charles Berger's guidelines for about 1.5g of sensitizer per 250ml of finished glop means 6g per liter of glop.
Based on some experiments I made last year, it doesn't seem like you'd want to pour thicker than 0.5ml per in^2 (and possibly thinner), so 50ml of glop for a 9x11" tissue. So that 6 grams of sensitizer would yield at minimum 20 9x11" tissues. 100 grams (~320 9x11" tissues) could be a pretty significant supply for many people.
Why not thicker than 0.5ml per in^2 (with about 11% gelatin)? Thicker than that, and the nitrogen that's given off by the azide breaking down can't escape all that well, and you end up with all sorts of little pinhole bubbles in the dark areas after mating and development (you can't see them in the dry tissue).