Paul there is a Master Cadena at El Mirador (Next town down from Sucina) & there is one in Dos Mares shopping centre just outside San Javier. You can download the current deals on their website : http://www.tiendamaster.es/Articulos.asp
Also there is Media Markt ( Spanish Curry's) at Neuvo Condo shopping park which is on the outskirts of Murcia. I got a 32" Sony Bravia for E550, last month, and that was cheap compared to the others. Also nearby is Ikea & Leroy Merlin (Spanish B&Q) plus Eroski Supermarket.
All electrical retailers will deliver if you give them time however they may not be open on sundays (Masters at dos mares in though, although the place will be rammed with locals on a day out, best go on a weekday morning!!).
Have Fun.