Sign up in-store for a PETsMART reward card. Buy cardinal tetra for 80 cents each (regular $4.49). There are many other tropical fish on sale for 80 cents using the reward card. Deal is good till tomorrow (4th of July). No rain check on live animal.
My local PETsMART just received a new batch this morning. Be sure to keep new fish in a quarantine tank for at least one week to avoid transferring disease to the community tank. White spot is a very commond ailment found on newly transported fish.