We've always rented for $150.00 or less TOTAL. We rent a small economy car and let the credit card insurance cover the vehicle. Our credit card insurance has a $0.00 deductible; the car rental company insurance has a $1,000.00 deductible. We've always rented from Avis because Avis includes the manditory 3rd party liability (required by Mexican law, so you will be purchasing it one way or the other) in the quote they give you. (I've heard that National also includes the 3rd party liability in the quote, but I don't know that for sure; I do know that Avis does--and it clearly says it does on the Avis web site.) For other rental companies (Dollar, etc.), figure on $5.00-$10.00 a day for the 3rd party liability on top of the rate they quote you.
Third party liability covers any damage you do to other people or their property--not the rental vehicle.
Anyway, we like the convenience of being able to go where we want when we want, and by the time you factor in the shuttle cost, you aren't paying much more for that convenience--not to mention taxi fares.
