The figures I've heard for a transformer in the Tortosa area is 24,000 euros - it may have gone up though.

Baix Ebre map, there are transmission lines close to where you are - but they are 110kV - they will be on large steel pylons - if you have cables on small steel pylons or concrete pylons with seperate wires then they are probably 11-15kV and you'll need a transformer - if they are on concrete or wooden poles and are all twisted together then they will most likely be 440V, from which 220V for domestic supplies is derived.

Nigel