The pellets that Clive is talking about are an "oversprayed" animal feed pellet.
There is a C.S.l pellet manufactured for the fishing industry, as a well known bait company and myself are involved in it.
If you put each in a glass of water, you will see that one breaks down leaving a pile of crumb whilst the other does the same but leaves broken maize grains and turns the water dark brown as it oozes corn steep liquor out of it.
The pellets Clive talked about, I actually did sell at one time, but were an inferior product but still caught fish.
As for £5 a sack, you get what you pay for.