I'm also doing a sponsored cycle ride (for some volunteer work in Nepal and the charity Send A Cow). So far I've raised roughly £1,300 for the "Li'l Big Adventure" as I've called it.
I've raised all this lot by
- Asking all my friends, family, assosciates, everyone in a cheery letter
- Dropping flyers and letters around local businesses (including writing to the local paper). Note that while I haven't had many replies from the flyers, it does get you talking to people and they might even sponsor you on the spot! [Hint: Always carry emergency supplies of forms and letters]
- Writing to my local school, promising to give assemblies and talks in return
- Having a houseparty with paid entry! (well I have just finished uni)
- Asking everyone at the Student's Union on a Cheesey Music night
I've also hunted down on the internet the addresses to as many bike and component manufacturer and retailer I can think of or find, which unfortunately aint that many (being a newby). Some have even replied!
I'm also in talks with the council over having a stand from which to proclaim the goodness of my cause.
A big problem I've found so far is that what with the tsunami earlier this year and the current famine in sub-Saharan Africa, a lot of people have already given what they can. A good thing, of course, but it makes our lives a bit more difficult! Just keep plugging at it is my game.
Hmmm. Reading your post it seems like you're already in Honduras, so I hope that some of this applies at least. I'm trying to keep the local interest in my efforts, but with big companies just keep trying!
I wish you every success!