Check out Rewarding Fundraising Ideas. You'll find a load of fundraising ideas that you could use to raise funds.
You should also start a Facebook page describing your cause and inviting all you friends to join and to help you with your trip/s by sponsoring you a small amount for it. Write a good emotive invitational letter that really encourages people to join the page and to help you out. Also encourage them to forward on that invitation to all their friends and family.
You could also consider doing a sports challenge to gain more sponsors from people, like a sponsored cycle, horse ride, bungee jump etc. I did a sponsored cycle in the UK two years ago to raise funds to get to film school and raised over 2000 pounds.
You should check out the "Free, taking to the streets" idea on Rewarding Fundraising Ideas. It's an idea that might work perfectly well for you.
Another idea which I always recommend is the Magazine Fundraiser! It works so simply. You get your friends, family and supporters to go to a special customized webpage of yours to subscribe to any of over 1000 magazines. Many of the magazines are on good discounts and you will always find people wanting to subscribe or re-subscribe to magazines. You will then earn 40% commission on all subscriptions, plus other milestone bonuses! It's a really rewarding fundraising idea!
Also consider the Credit Card Fundraiser!
Good luck, I hope it works out for you!