It's very easy to get a cell phone in Mexico and you will not need to sign a lengthy "contract". I suggest going to Telcel. They are located throughout Cabo San Lucas and San Jose Del Cabo. The main Telcel location in downtown Cabo is directly past the Pemex gas station and at the intersection of The Cabo Bakery and City Club.
The best phone to get is the cheapest! You can get an expensive phone but why bother. If you lose it, it is no problem! For around $20 USD you can get a phone that is preloaded with minutes. Telcel will ask for your passport so make sure you bring it with you. I suppose this is their "safety measure" to crack down on the drug dealers purchasing phones and not knowing whom they belong to?
Remember your cell phone number. To add minutes to the phone, you can go to your nearest OXXO convenient store to "add" minutes. The clerk will ask for your cell phone number, how many pesos you would like to add and then you will receive a text message from Telcel acknowledging that you have loaded more minutes to your phone.
If you don't use your phone for several months it will become deactivated and you will lose the minutes that are currently on your phone. To reactivate, you just need to add minutes to the account. If you go more than 6 months without using the phone, you may even lose your telephone number.
If you need to reload minutes and have access to WIFi, you can purchase minutes online. www.pinzoo.com is a great website that is easy to use. You will select "international", click on "Telcel Mexico", and then select how many dollars you would like to add. Pinzoo does not charge tax and the minutes are added instantly to your phone.
These phones are able to call or text the United States. It will use more minutes than a local call. If you don't talk much, 100 pesos added to a phone goes a long ways!
Most Americans own a smartphone. When you arrive into Mexico, make sure you turn the cellular data "OFF". Your cellular company will charge an exorbitant amount of money if this is "ON". Most businesses in Cabo offer free WIFI to their customers. If you are in a restaurant, the password is usually printed on the menu.