Ask HN: How can I raise $250, fast?

I am the lead welder, engineer, and machinist for my high school's Kinetic Sculpture Team. We participate in the Kinetic Grand Championship (http://www.kineticgrandchampionship.com) and the race is coming up in about 60 days. We have been working really hard and just got all 4 wheels attached to our sculpture yesterday. What we need now are two steel framed mountain bikes in good condition. We haven't been able to find anything within our budget on Craigslist (really rural area) and I have decided that we should just buy them. There is a local store that has exactly what we need for $100 apiece, but our team just doesn't have the money. We are a sort of under-the-radar club at our school, organized as a community service project. During the race, we raise money for a local homeless charity. Unfortunately, during the offseason, money really dries up. I have taken it upon myself to raise the money and I figure we will need around $250 in total for the two bikes and tax.

I am coming here because I know how good y'all are at fundraising and finding what South Park would call "internet money". If anyone out there could point me to a site that is designed for this type of quick, small fundraising, that would be great. I am also down for any other ideas that might help us.

Here is a picture of us yesterday (I am in the middle) http://imgur.com/9ETOpci

Here is a picture of our team in last year's race as Betty Chinn's Peace Crane http://imgur.com/JfVxieR

Thank you! Mr. Meker