You will be able to get at least 540 from Scotia Bank in CR

I always get the best rates, no matter where I am, from an ATM.

Banks in the US and airport currency exchanges are not going to offer any where near the best rate.

For banks in the US, currency exchange is a 'special order' and there's heavy fees. Airport currency exchanges make money off the conversion.

The current 'official' rate is 553 colones to $1 USD. You were offered CRC 480 per $1 USD. That's CRC 73 less. $13.24 loss over $100.

The best rate is going to be from a bank (or bank ATM) in Costa Rica. Tell your bank you are going to CR so your ATM card works (if you don't, it won't).

I always get the best rates, no matter where I am, from an ATM.

I haven't found an AT in the US that dispenses colones...

Which ATM do you use

I haven't found an AT in the US that dispenses colones...

You will get terrible exchange rates if you try to get colones outside of CR. My bank made a huge deal out of having currency available at the airport (Toronto)... picked up some and ended up getting dinged almost 10%. Taking money out via ATM in Costa Rica costs me a $5 fee at home... plus the built in fee around 2.5% (difference between posted mid market rate and what I actually got). You may be able to do better than that with US dollars. So use US dollars after you arrive in CR until you have a chance to either withdraw colones from a machine...or get to a bank and exchange dollars for colones.