My son hasn't worn the blue blazer and khakis since 7th grade Bar Mitzvahs! He does have a pair of dress khakis that he wears with a nice shirt and tie for some performances, but no blue blazer (now he'd say that look is too preppy).
He has a dark suit that was actually a hand-me-down from my H, who <ahem> outgrew it. He wears it many, many times a year, but in several of his ensembles, dark suits, shirts and ties are the norm.
You can buy a decent suit for a young man for well under $200. We bought a used designer tux at a resale place for $75, and it looks better than a $400 one. So, I'd look resale too.