I recall being told that the vast majority of pellets are produced by only four different manufacturers. Obviously they have become very popular and some tackle companies do make thier own, however certainly a few years ago before the pellet boom Angling was a very limited market compared to aquaculture. The quantities that get used up by commercial aquaculture are astounding. In some cases we are likely paying for marketing but I expect it’s often grading too, if the feed is no longer suitable to feed to animals for human consumption etc. Often a give away with cheap feeds is the ash content, lots of cheaper feed stuffs will contain significant amounts of ash as a Phosphate donor for growth as apposed to more expensive ingredients. I doubt most fishing baits give that kind of break down but you could ask?
For the last few seasons I mix and match, using cheap halibut pellet as a bulk feed and a quality of more premium pellet added for draw. For example, without giving too much away, I may use 70% generic halibut pellet, 5% boillie, 25% premium boillie marching pellet. This reduces cost significantly and I don’t think it detracts from the attractiveness of the bait and baited area.