Came across this website which allows you to calculate (roughly) the cost of a taxi fare in Portugal. Just type in your starting point in 'Inicio' and destination in 'destino' - supplements include luggage (bagagem), call-out charge and night-time/weekend costs. Tariff 3 applies to us here. Suitable for FAQ?

http://www.antral.pt/simulador.asp

Seems like an excellent link.

Can anybody confirm how accurate it is?

With car rental getting very expensive in the peak season this allows you to price alternatives.

Suggest you PM Steen to get it added to FAQs.