Hi Ness, get Mexican insurance on line, Mexpro.com seems to be the best deal if you have a Canadian license, if you are on a Brit or International license use Sanborn.com. Six months seems to be cheaper than 1 week. Insurance is not compulsary for Mexico but having it will keep you out of jail if you have an accident, guilty until proven innocent is the name of the game in Latin America, they will impound your bike until blame is decided but the insurance lawyer will protect you from being incarcerated. Guatamala was US$12.00 at the border but as for the rest of CA I would say check at each border and if you do buy, remember that you will be returning and usually buying a 3 or 6 months period is cheaper than 2 lots of 1 month. Ride safe.
Mike is riding the twisty road in the sky