http://www.erideshare.com/
I know a kid who went from boulder to alaska and back using just this site. you may also go to a local truck stop and ask truckers they will help you out you usually gotta supply something to help them out weed, meth, sex, booze, but you'll make it there.
WHy don't your parents or sister help you out? I mean this is kind of a big deal and I find it weird they won't buy you a ticket to Vermont... for your sisters wedding... that you need to attend but can't.. because you have no money.