Self test in Barcelona Pharmacy is about $5 each. If you want certified test you buy self test and take test in front of pharmacist who will write up and sign certificate of result for $10 extra. Test for boarding and flight home were performed at pharmacies closest to hotel and the hotels were different each time. Procedure was the same. If you are not happy with the result of test in front of pharmacist, there is no compulsion to pay for certification; but if you need official result for insurance claim, the certificate is necessary.