The equipment suggestions sound excessive -- if something major goes wrong, you could get a brand new bike adequate for a cross-country tour for under $1,000. If you have a frame failure, you can probably find a similar vintage mountain bike for $100 or less and move across any parts that are better on your old bike than the new one. No need for custom-built wheels, just have a good shop tune and tension your factory wheels.

To my mind, the real variable is how much civilization you need along the way.

Riding solo from Seattle to Los Angeles, I spent most nights in a bivvy sack, often without even paying for a campsite. I doubt I spent $500 the whole way south, and most of that was for pie at diners ;-)

Riding around Ireland for a 1,500 miles or so, I spent many nights in hostels or B&Bs, ate in restaurants, and probably spent five times as much for a shorter ride.