sounds a bit expensive, just think about the huge house you could build in central portugal for a 6th of the cost of the Algarve. Unless someone really wants to live in the Algarve they would be far better off building thier dream home in an other area as it will mean for the budget they have they could have a bigger better quality build with much more land around them. still close to major airports in a much nicer landscape, where the scenery is mountains, rivers, lakes and forests. not too mention the far cheaper cost of living where you can still have a 3 course lunch in a top resturant for 15€ and a normal resturant costing around 6€

take a look at some examples on
GekkoPortugal: A guide to Living, working and buying property in Central Portugal