Try Mangrane in Ronda Docs, near the station but on the other side of the railway - if you enter Tortosa from the L'Aldea end then take almost any street on your right, go to the end, turn left then follow it along - that's Ronda Docs.  It looks like (and is!) an old railway shed.  They sell cheap tiles there - they also have a showroom on the N340 between L'Aldea and L'Ampolla (big red warehouse on the left).

Alternatively try Mayors - they have all sorts of tiles there - you'll see their sign on one of the roundabouts on the Tortosa to L'Aldea road.


Nigel