My son had to wear a dress jacket or blazer for boarding school. Of course, once he got to school we didn’t see his Navy blazer again until the end of the year. We also ordered an official school blazer for him during orientation. When he came home at the end of the year, the Navy blazer was about 3 sizes too small and had grotesque stains on it from a “shaving cream incident” that took place “oh, in September, or maybe early October.” We never saw the expensive (optional) school blazer. Ever. That was delivered directly to him and later destroyed when he used it as a makeshift levee to stop an overflowing toilet from spoiling the carpeting in the hallway of his dorm. Your purchase decision should account for these sorts of parent-puzzling supervening events.
For his part, he didn’t mind having one really nasty blazer. If anything, it was a way of complying and playing by the rules without being utterly submissive. (He never articulated that last part. I just imagine that was where his head was at from my overall view of things.) This is not to say just ditch him with one jacket and never check up on it. That’s what we did and that’s basically negligent. I think you have to gauge your child (without imprinting your own values/wishes onto him) and go the cheapest route feasible given your child’s tastes and comfort level…oh, and interest level in girls who would (hopefully) not be attracted to the guy in the shaving cream-stained blazer.