Apt rentals in cities like Cadiz and Valencia cost less than the 20.00/m2/month that Porto costs. https://www.idealista.com/alquiler-viviendas/cadiz/playa-victoria-paseo-maritimo/con-precio-hasta_900/

shows lots of apts costing 10.00/m2/month.

I used the Airbnb example to put a ceiling on shorter term rental costs while looking for a long term apt.

When buying = more than 18-20 years of rent it doesn't make sense to buy unless you're young enough to get a 70% LTV mortgage. An older cash buyer greatly reduces his income by tying up capital in an apt whose value he won't live long enough to amortize. That's why we rent in Porto, while my wife's daughter and her husband bought.