Going to Portugal in Sept from Miami. Wondering if anyone has ever bought one way ticket over there, then 3 weeks later book a return flight home. Not sure of buying return trip over there. Is it cost effective. Heard flights are much cheaper over there. Thank you for your help.
Whether you can save with two separate one way tickets or one round trip ticket I don't know. It probably depends.
However unless you hold a long term visa, such as an Habitual Residency Visa granted by Portugal to those who intend to move there, to enter the Schengen Zone without a visa, you need a round trip ticket in your hands or you may be denied access to the country.
When I have looked at buying one way tickets, US to Europe, I have found the cost of a one way ticket is as much, and on occasion more than a round trip ticket. Multi city ( aka open jaw) are usually so close to the same cost of of round trip the difference is meaningless.
If you can find a way to buy one way tickets for less, great, but I think it is unlikely