If I where you I would by 15 or so pounds of dry rack and a few pounds of live to "seed" the dry rock. Live sand would be good as well. Then all you need is a heater and thermometer power head and bam you got a fowlr
Fish Only With Live Rock tank!
Just be sure you let the tank cycle. I know it can be tempting to just throw some clowns in right when you set it up. But you gotta make sure there is 0 ammonia. 0 nitrites. And low nitrates. Then you'll be ready!!! Lol good luck! I hope your son likes the tank!!!!