I pulled off a couple of charity rallies. Note: all of my experience is based on Canadian laws, rules and regulations.
Insurance: Get a local insuurance agent to sponsor you. If you know a local motorcycle friendly agent they will often trade a one day coverage policy for all the free advertising. It's free advertising if nothing bad happens. The other option is if you have a local bike shop with a big parking lot. Our local shop hosted our event and called it a customer appreciation day in support of our charity. We were covered for the day for insurance and he got a crapload of customers in his shop checking out his bikes---win win.
Raffle items: Go around to local bike shops, grocery stores, tattoo shops, hardware stores, yoga studios, basically any store you can think of and ask if they would like to donate to the event in exchange for advertising. I have gotten everything from lawn chairs to display model helmets (worth $200.00) to a gift certificate for 1 Hour of tattooing. A lot of shops will give gift certificates. It cost them nothing to give away and it just might never be cashed in so they lose nothing.
Food: Talk to a grocery store. The big chains are the best, they have the most money. Many of them will give a huge discount or even a food donation to put a banner on the front of your barbeque. You can never lose money on selleng $2 dollar hot dogs and $1 pop.
Music: As stated above radio stations might help out. Another option is to go to your local college, university or even high school and find a local band. They will normally play for free just because there is an audience and good exposure. Music shops may be a good place to look as well. It's pretty likely that the slack-jawed teenager behind the counter is either in a band or has buddies who are.
Booze: Agree with JamesB- We always avoided it. That and liquor licences are expensive. At the end of the day you want everyone home safe. You can always go for a pint after the event is over and done with.
Good Luck Tugboat....Hope this may help you out..
Operator