A tip I learned while looking for a place to throw a surprise party years ago:
If you don't have enough space to host a party or event yourself, rehearsal studios will rent out rooms to just about anyone for cheap. Think especially classical music studios and dance/theater studios -- basically big rooms with wooden floors, lots of windows, and lots of space (and the expectation that things might get loud). Rock-type music studios are also an option, but the rooms tend to be smaller and, frankly, scuzzier. Useful for parties, gatherings, gallery events, etc.
I'd needed to throw a party in Manhattan quickly and cheaply that could fit a few dozen guests and a live jazz band. Traditional rental spaces were way too expensive ($200+/hour), and many clubs/restaurants were either too expensive ($50-$100+/hour), wouldn't allow a live band, wouldn't allow food, and/or required hiring their own caterer for food. Guests and I planned to bring food, beverages, and decor: all we needed was 4 walls and a floor. Eventually I hit upon the rehearsal studio idea since they expect music/live bands by their nature, and while some rooms are tiny (for 1-2 people), some are sized for orchestras, plays, and dance rehearsals. Add band and guests = instant party.
The rental space (with chairs and tables included) ended up costing about $100 for a 4-ish hour party, which they even allowed us to go over since no one had the space booked after us. Worked out really well. Just make sure food is allowed when you book.
