Think outside the box to find ideas of things to do. People hate selling stuff and people hate getting hit up on stuff being sold so try to avoid that as much as possible.
This past weekend we did a fundraiser that got us over $1000 and will probably end up just growing each year. It was a softball game between our faculty and members of our community BUT each member of the team HAD to wear a dress, purse and woman's hat. Let me tell you that it was one of the funniest things I've ever been part of. Everyone had a great time and people are saying they are coming next year who didn't come this year. I can give you more details about it if you want.
Another fundraiser I've had success with is Powder Puff football. I put each class as a team so obviously there were 4 teams. To be on a team they had to pay $12 which bought them a shirt. I got a pretty cheap place to make the shirts for around $4 - $5 each. On the night of the game I split the field in half to play two games at once. Both 40 yard lines were goal lines and the 50 yard line was the back edge of the endzone. Get guys to coach the teams. Once the first game was over the two winners played for the championship and the two losers played to get another game. I never charged admission or concession but you would make money if you did.
It's not short notice but a golf tournament makes a lot of money if you do it right. I would give 6 months head start to plan a tournament.
Another not short notice is I used to put on softball tournaments in the summer. $100 entry fee and concessions. We used to make around $1500 each tournament but it's a lot of work.
Something I'm going to do when I become a head coach again is put on an X-Box Madden tournament. Haven't figured out all the details but with the way kids love to play video games surely it has to be successful.
Hope some of these help or spur you to think of some stuff to do that can help you. Good luck.