If He is set on getting a symmetrical and only weighs 80 pounds he might want to consider something like the Line Afterbang Shorty in the 144cm. It's not too expensive and as far as durability in the park the skatedeck construction holds up really well. If he is worried about outgrowing a 144cm ski to quickly the Atomic Punx is made down to a 155cm and they make a junior version which is pretty much the same thing just cheaper in a 150cm length which are both symmetrical. I own a pair of Afterbangs and after riding the Punx in February I am trading out for them because they are super poppy and really light weight. The Punx is a bit more pricy at 399 but it is alot of ski for the money. If he has changed his mind on wanting a symmetrical ski the K2 Domain is is a good thought or the Line Mastermind is pretty reasonably priced and a pretty solid ski, but the cap construction does chip and wear a little fast.
The company I work for has last years afterbang shorty still if you are interested