Our club does group buys of this stuff once or twice a year, and order in something like 20 packs frozen. It think it ran me $35 or $40, but the small bar at the LFS ranges from $5 to $8 typically.
For the sized tanks you guys are feeding, that will be plenty. With my gigantic tank, I need more and at any savings I can muster.
If you'll look at your brain coral at night, it should extend some feeding polyps. Use a flashlight instead of the tank lights. If you see them, that is the time to feed. Usually about 1 hour after the lights turn off. Now you can feed the coral, but turn off the circulation to avoid it blowing away. If you have shrimp (aka thieves), cover it with the top half of a 2-liter bottle. This will allow you to feed through the top with a syringe or turkey baster, and keep the bandits away.
If you think you'll be forgetful, drill some holes in the bottle to allow a little bit of circulation in the dome.
And once the dome has been pressed down around the coral, you can turn on your pumps again. I press it into the sand, but others have used a hot glue gun to glue on some glass beads around the base of the dome to keep it from blowing/floating off.