Viña Pati Rueda from Lidl is particularly fruity - latest batch I've bought is 2011, perhaps a good year? I'm sure it has gone down in price as it's only about 1.60€ a bottle now.
Reds we tend to be a bit fussier over. Our fave is Faustino VII for about 3.60€ from a wine shop in Nerja - it's the cheapest we have seen it.
Yes, it's €1 cheaper than it was but it has also changed slightly. They now use a mix of grapes - Verdejo and Viura, it used to be Verdejo on its own at about €2.59. They also sell a Rueda "Visigodo" which is about €2.69 which is just Verdejo. I have tried blind tasting both of them and they are almost identical. If you look at the labels they both have the same logo (a tree with starts in it) so they obviously come from the same bodegas.
It's definitely the best value white Rueda by a mile. I know quite a few people who used to insist on drinking Marques de Riscal Rueda at €7 a bottle who now drink it. OK it's not quite so good but at that price it's unbeatable.
If you want a change from the Faustino Rioja try Lidl's Ribero del Duero called Hachon. There is a reserva and a crianza but the cheapest one at about €2.59 is pretty good.