Price will vary greatly upon where you live, season, other events in the area, etc. Not to mention your tastes, if you prefer chicken you aren't going to pay what someone who has filet mignon and lobster does, though your event can be every bit as elegant. Same goes for flowers, it's possible to have a lot that cost little or a few that cost a fortune. Champagne doesn't have to be pricey to taste good (I highly recommend taste testing the brands your banquet facility offers).
Ours was $10K fifteen years ago. Formal, not ultra-formal. May wedding, 125 people, church wedding, banquet hall reception, live band. Everything except open bar and limo (DH had to use his 'baby'... sold it when we had a real baby, lol!). We live in a rural area, probably saved a couple thousand. Almost forgot, didn't pay for musicians other than an organist, my mother was our soloist (beautiful, but she almost lost it once when she looked at us).