I live in CA and grew up here. My parents were poor but loved a good family road trip. We camped our way across all of the western states growing up and visited many national parks etc. My son is now 8 and has packed along on many 9-10 day road trips with me. If we want to go, we usually drive because it's cheaper. If it's that important, you make it work.
I don't see $2,500 as an impossible number to work with if this really is the end all be all trip for your son. Recycle cans, rake leaves, walk the neighbor's dog, pet sit, babysit other people's kids for money, eat vegetarian 2x a week, sell random junk on craigslist. In high school, before I was old enough to get a work permit, I desperately wanted to attend a summer program in Australia. I worked for an entire year doing odd jobs, to save up the $3500 necessary to make the trip. I asked all my family to give me money for my birthday instead of gifts. You take the $5 or $10 and save it and turn it into the once in a lifetime trip.
