First off a VARIETY in your fishes diet is the best thing to feed them. I've found over the years that alternating between two or three different types of foods on a daily basis, as well as supplementing with treats once a week (frozen foods, live foods, whatever) will bring out more vigirous behavior in your fish.
Secondly you need to describe what cichlids you're talking about, and their age.
For the first 1-2 years a high protein food such as Hikari Massivore or New Life Spectrum Growth will help your fish in achieving it's full potential into adulthood. But depending on the species of fish you're caring for that could change.
Fish foods I always have on hand:
Hikari Bio Gold
Hikari Massivore
New Life Spectrum - sinking pellets, growth, large fish formula.
Omega One flake foods
Freeze dried krill - usually the hikari brand in a bottle. Krill has the highest protein content when freeze dried out there, bar none. It also contains chemicals that will greatly enhance yellows, golds, and reds in your fish.
Always have some sort of omnivore food to give the fish at least once or twice a week. The kelp/seaweed will help keep their guts moving.
As far as purchasing - buy in bulk. You can spend around $100+ on fish food, but that supply will last you half a year or more. Check with
www.marinedepot.com www.drsfostersmith.com www.bigalsonline.com
John_PTC, one of the moderators on here, also sells massivore in bulk - I believe.