We were looking for a cheap lap top and looked everywhere and the cheapest we could find was 499 Euros (including Carrefour, Alcampo, Ideal, Boulanger).
We´d discounted El Corte Ingles as we assumed it would be way too expensive but looked there as a last resort and managed to find 3 in there for less than 499, the cheapest being 399 Euros. We even managed to get an extra 50 Euros off!
This was however the small Corte Ingles in the centre of San Pedro which just sells electrical items (next to the large Supercor), so you may have some luck there with a TV. It´s definitely worth a look.