Feed prices are based on ingredient pricing. Fish meal has jumped in price due to low harvest of Peruvian anchovy and because corn prices have skyrocketed due to ethanol production. When corn prices went up, so did many of the other grains.
"Cheaper" feed is made with cheaper ingredients. Based on your goals and the species you feed, that's how to choose the best feed and work within your budget. If you want to grow huge fish, you must use a feed with adequate fish meal. If you want to grow fish for fun, or raise fish such as catfish or tilapia, grain-based, less expensive feeds may work just fine.
