6K just for 120 per night in hotel. Prolly cheaper but lets just say that.
1. I would estimate you trip is gonna be around 15K - 20K USD EASILY maybe more.
2. Depends on where you want to start.
3. Gas Differs from place to place, anywhere from 3.40-5.00 per gallon at the moment.
4. How to save costs? Sleep in your car. Get a gas efficient rental, i.e. hybrid. Dont take the trip
