To be honest there are pro's and con's to having a car in Los Cabos vs. taking taxies or vans. Once you leave Los Cabos Airport there are a few options and preplanning is your best option. At the airport, upon exit, you have to leave through a timeshare rental room (ugh) then through a transportation room before you are out. There are many people there that will approach you to sell a ride or shuttle. The prices will vary but remember that they are all there to make a commission. Prices quoted will be all over the place.
Cabo airport shuttles will leave every 20-40 minutes as they wait to fill up a van of 10 passengers. You'll pay anywhere from $18-$30 a person depending on where you are going. The important thing to remember is that with Cabo Airport Shuttles you will likely have 3-5 stops before your destination. So getting to your resort could take 1-2 hours because of stops. Your other option is a private transfer from Cabo airport. Depending on your group size you get a Suburban, Escalade or van, free beer, and water and go directly to your resort/destination. The price will be from $59-$150 again, depending on location.
Now ask yourself - what is the cost of my 1-2 hours in transit on "my vacation?" There is where you define value. Best bet is to look at SJDtaxi.com online before you go. Get the best price and have them waiting and ready when you arrive.
As far as renting cars in Los Cabos, you need to be ready for the crazy Mexican roads and drivers. It's not the USA and that rental car logo on your car opens you up to local scammers too. The cost to get a car all depends and there are a number of car rental agencies in the airport or, on the grounds to be transported to. Be prepared to spend a few dollars and careful with insurance and credit card coverage. Know before you go.