We made a small wedding in Monsey (for ourselves, mostly paid for by our parents--we preferred a "block grant").
It was smallish (200 guests, Sunday wedding during the post Purim "season") and it was about 20k all in - hall, photographer, 5 piece band, photographer, video (should have nixed that in retrospect), flowers, wine, invitations (mostly did paperless). If we wanted to, we could have cut down on band and done it for closer to 17k.
Othwr than video, I don't have regrets.
Adding an extra 100 people wouldn't have driven cost up so much. The hall we did (a small one) had a minimum, and the marginal cost per couple was pretty low beyond that.