Taxi Cost depends on time of day/night/weekend/bags.
Estimate between € 85.00 and £ 115.00 each way.
Its often more economic to take a hire car if here for up to 2 weeks if a family of four.
Search this forum for recommendations on airport transfers.
Two companies to look at include:
Low-Cost transfers - http://bit.ly/9UdwBj
and
Algarve365.com - http://www.algarve-365.com/