It has its critics but there's something to be said for tradition in all walks of life. The same is true when it comes to raffles: there are all kinds of variations, but a traditional one is one of the best and most profitable events you can hold for your fundraising group.
As part of your preparations, get in touch with local businesses and explain who you are and what you're raising money for. See if they will donate merchandise, gift certificates or anything you can use as a raffle prize. You can then pick up a big roll of two-part tickets from a party supply store (they shouldn't cost very much) which can be sold on for $1 or $2 each.
For their money supporters get one half of the ticket and the other half goes in a large container (it could be a bowl, bag, box or anything suitable). When it's time for the raffle, the tickets are all mixed together and drawn out randomly one at a time.
The person who has the other half of the ticket wins the prize. It's your choice whether or not ticket holders have to be present in order to claim their prize, but the act of handing over the winnings does add to the enjoyment (and saves you having to store items for later).
If you can get a good range of donated prizes, your only outgoing cost is the money for the raffle tickets, so it's a fundraiser will plenty of potential. Make sure you double-check your state and/or local laws regarding raffles and abide by them at all times.