Many choirs sing at concerts to raise money for various charities. Why not do a concert to raise money for your choir?
If you know someone who would donate a venue for you to use, you'll be ahead. If not, you need to figure the cost of renting a building into the amount of money needed. If your choir is well known in your own local community, you might raise a lot of money, even enough to offset the cost of renting a building.
Raise money by charging a small donation amount, perhaps $10, to see the concert. Another option is to collect free will donations at the concert instead. More people might attend, and you might raise more money, if you give discounts to senior citizens, students, or even the military.
Send out press releases about the concert to local newspapers, radio stations, and television stations. If your choir is part of an organization which has a website, you might want to publicize the concert there. In addition, make certain the members of your choir tell all their friends and relatives about the concert. They may even be willing to sell tickets, if you are selling tickets before the show.
You could sell food or drinks at intermission. If you wanted to raise additional funds, you could even ask local businesses to donate food or other items for a raffle.