I was heavily involved in FIRST Robitics Competition in high school, we started a team back in 2009. Our registration fee was $6000 for one regional competition and the kit of parts, plus travel expenses for 20 people, plus tools and spare parts. We have managed to raise enough money each year that there is no cost for students to participate, even for going to a competition 4 hours away for 3 days.
Most of our fundraising comes from sponsors every year. Many of them have been with us from the beginning. For example, a local bank has paid our registration fee ($6000) every year.
http://team3044.com/index.php/learn-about-us/sponsors
The best advice I have to any team is to reach out to every local business and local tech company they can think of, especially if they have a connection to the team through family members. Provide advertising on the team website and the robot in return, and be prepared to take the robot out to any school or community events where students are involved. Town parades, school activities fairs, technology expos - they're all great ways to get word out about the team. The more well known they are in the community the easier it will be to find sponsors and raise money!
Good luck!
Kelly