While technically still in Porto, on the other side of the River Douro, you have Vila Nova de Gaia. While many residents on the other side of the river (Porto city side) joke that the only good thing about Vila Nova de Gaia is its incredible view over Porto, this is unfair.
Nowadays, Vila Nova de Gaia has some of the most beautiful areas and you can find much cheaper properties on this side of the river. Additionally, Vila Nova de Gaia is still incredibly famous for its Port wine, where there are over 60 port cellars.
Also close to vast stretches of beach and with trendy restaurants opening to cater for the increasing interest in houses here, this is a great area to live in. Close to Porto city and not far from the best beaches in the north, such as Praia da Madalena, this could be a very viable option for you.
Vila Nova de Gaia is served by the metro line, bus services and railway services and is only 30 minutes away from the main universities.