Not having a local bank account is not a problem, you have three very good and safe options to pay for a car in Costa Rica.
The first one is doing an international transfer from your bank anywhere in the world. The estimated time frame for this is up to 72 hours, depending if your bank has to go through other bigger banks to do the transfer. Bigger banks that offer the international transfer service will take minutes to transfer the money to a bank in Costa Rica. In our experience, it has never taken more than 48 hours, and normally less than 24. It is a good idea you check ahead of time with your bank if they offer this option, so you'll be prepared and the car purchase won't take too long.
A good idea is to transfer the money to someone local of your trust instead of the buyer, so there won't be that moment of uncertainty while waiting for the money to arrive.
And something important to consider with this option, is that the banks will ask for proof of funds origin, if the amount is over $10,000. So have that info ready before transferring the money.
The other option is paying in cash. This option is more feasible for lower budgets, since you have the option to bring cash with you on a plane. Each person is allowed to bring up $9,999 on a flight. Normally a car seller won't accept cash immediately, anyone will prefer to go fist to a bank and deposit the money on their accounts. Cash is not king in Costa Rica, and doesn't work to offer cash as a point of negotiation.
Credit or debit card. This method applies only for purchases on car dealerships, since individuals won't have a way to take a payment with this method.
Methods that doesn't work in Costa Rica:
❌ And some others of these same nature
We do these car transactions on a daily basis, and have a vast experience dealing with payments and possible roadblocks, so please do not hesitate to contact us with any question you may have about this.