PE is good stuff, and very convenient in cubes, but if you go through enough of it, it gets pretty spendy.
There's a place in NJ called Jhemco. They sell Mysis in 5# blocks for like 30$. They also sell Cyclop-Eeze, but I find that I don't use it fast enough and it gets freezer burn. I know it's not what you had in mind, but you may find that you like the bulk approach.