I just shovel up what's under the cages and bag it. I do make some effort to distribute the hay/wood shavings/fur/dropped rabbit food kind of evenly among the bags, partly to give the buyers a better fertilizer, and partly to make the weight more even for me to handle (it's a bummer to try to move a 100 lb bag of wet poo while other bags are 30lbs because they're mostly hay).
I just note on the craigslist ad that they are "50lb feed bags full of rabbit poo, also containing varying amounts of rabbit pellets, hay, pine shavings, and shed rabbit fur." I also note that the feed is no "corn/no soy" if that's what I've been feeding them.
I have waiting lists both spring and fall for bags of manure; I generally can't shovel fast enough. Last year I sold 106 bags, roughly 5,300 lbs of fertilizer. Makes me tired just thinking about moving that much weight by hand, shovelful by shovelful... and that doesn't include what we used in our own gardens. But my bottom line is happy.
