Depends what type of cichlid they are. If they are convicts, kribensis or ones like that, chances are the pet store won't even take them.
When I had my pet store I didn't put a percentage mark up on mine. Goldfish if I paid 70cents for them I sold them $3 each or 5 for $10. The likes of oranda's, pearls, bubble eyes, I paid $6 sold for $10. It depends on the species, some are easy sellers so can put 3x mark up on them, others will sit and grow big and won't let you use the tank for anything else so I use to price them to sell. Even my full grown Oscars - I sold for $50 but that is just me and now my pet shop is non-existance so obviously i went wrong somewhere. But I had a goal to profit on my products and not so much on the animals but something backfired on me. If a business doesn't cover their costs and make profit above the costs, you go down hill.