Mann lake sells 50 bags of brewer’s yeast, cheaper than pollen sub.
I priced soy isolate found it is very expensive. Thought about adding it to a commercial sub.
What commercial subs have you tried, which ones were not being consumed fast enough
More water or oil so that it does not dry out.
A few drops of wintergreen EO might keep the beetles out, I hear they don’t like it. It might keep the bees off it too. Might also try Thyme EO bees will eat that but I don’t know about the beetles.
You may have read these already, there is some good info on subs.