Oregon has no sales tax but being a out of state person you might not have to pay Cal sales tax. Az will not charge sales tax if you buy a used bike from a privet party. You will need a address so the DMV can mail the papers on the bike. You will need to have the papers for the bike to clear into Mexico so you can get a import permit for the bike and your stuff you bring in. This is a great plain and will be fun to pull off. Find a safe place to stay at night, but a guy on a bike should be OK.
02 BMW 650GS DAKAR
02 YAMAHA WR 426 Plated