Christopher Columbus landed in Costa Rica (Rich Coast). The money is therefore the colones (Spanish for Columbus.) 1 colones is not worth much vs. the dollar.
There is an ATM at the airport to get colones when you land. Check with your card issuer to see what the charge is. It may be a percentage plus a transaction fee.
American Express in the states may sell you some before you go. But, they discount heavily and then also charge a transaction fee.
Prices are quoted as C (substitute a cent sign) and the amount like our $ 1.00.
Take a calculator if you want to do accurate conversions.
Some say that places that quote prices in dollars are more expensive than others. Or, maybe they just deal a lot with tourists with dollars.
Not everywhere takes dollars or credit cards.
If they do take credit cards, you should get the current exchange rate on your bill. But, check with your card company to see if they have an exchange charge. One has a rate of only 1.0.%
There is an exit tax to pay at the hotel or airport. At the airport, they take dollars, colones or Visa.
Get and review restaurant bills to look for charges for extras.
NEVER EVER use a money exchange window in the San Jose airport! While you will be treated fairly in most other locations, that place will gouge you badly. You can pay for your orange cab outside with a credit card or dollars.
You will know if you know the accepted exchange rate before you land.
Go to : finance.yahoo.com/currency-converter for table and current rate for your currency into and out of the colones.
WARNING: Be very cautious of the money changers you will see in downtown San José. These people lurk outside the banks waiting for people who do not have the time or the patience to wait in the long banks lines. They do a money switch thing which is really clever to watch and you end up with less money, the wrong change, or counterfeit bills.