Safest way to travel extremely low-budget?

Any advice? My bro and I are still kind of young, I can not walk long distance due to health issues, and we don't have much cash. We are in Portland, Oregon and are mostly interested in Seattle, Chicago, San Francisco, and NYC. I am especially knowledgeable of Seattle and somewhat of Chicago as I have been to both. Any cheap buses or anything else?
 
Put one foot in front of the other, on the ground or a bike pedal.

He's got me beat on the motorcycle idea. I've met people who hike the Pacific Crest Trail. I prefer to hitchhike, I've never had any problems with safety yet, but I'll be preparing myself with some self defense classes soon.

Go look on the bulletin board at your local college.

What would one look for on a bulletin board at college?