That's great that you were able to trim those poopy butts! So satisfying to get rid of it that easily. Now, if you have a farm supply store, like Tractor Supply, or even a Walmart, nearby you will find layer crumbles a lot cheaper than Amazon. Though you will have to buy in larger quantities...
I also give my girls "treats" every day, mostly scraps. I do try to watch the sodium content and I seldom give them anything that's highly processed. So, you might check the salt in what they are getting and maybe trade out the processed rice rolls with unsalted popcorn. Also, have you tried...