I can easily imagine dropping $2,500 on work clothes, but at that level, it feels like we’re talking about a want more than a need.
Yes, suits are expensive. However, particularly when we’re talking about ultra conservative suits, they also tend to all look the same! I hardly see how a person would need five of them when they’re first starting out. Buy one nice but forgettable navy suit, and one nice but forgettable black or charcoal suit. As more money comes in, add a tan or gray suit. You could easily re-wear a suit once or twice in a week without anybody noticing, so long as you mix things up with a different shirt underneath and perhaps different accessories. Then get dry cleaning done on the weekend, if needed.
Particularly assuming that a person has a few usable basics to start off with, I wouldn’t recommend spending more than $600 or $700 at first, and then gradually building upon that as the paychecks come in. Starting off with five gorgeous suits might be nice, but it hardly seems like a “need” unless you have some extremely observant and fashion conscious co-workers.