In 1979 I rode my cheap bicycle from San Francisco to New York, with detours up to Oregon and down to Texas along the way. It took me three months of leisurely riding, with no training up front. I think I spent $500 for the whole trip. It was of course, a blazingly glorious journey, and not that hard. My rule of thumb was to never pass on opportunity to snack along the way, mostly as an excuse to stop and chat with whomever was around. I burned through a lot of junk food, but learned a lot about the US.