Spain`s not really a country for saving money.
The costs compared to most EU countries, the UK included are around the same at the end.
If your used to 4,000 Euro`s a month, you may find it a struggle, I don`t know the actual cost of living in your country.I took a drop in pay to live in Malaga from the UK, it does take some time to adjust doin the same job for the same company less money.
For research you may find lookin at the net for shopping and compare the prices.These are popular in Malaga city and Spain.
http://www.compraonline.grupoeroski.com/ecoventa/tienda/tienda.jsp
https://www.mercadona.es/ns/principal.php
http://www.carrefour.es/supermercados/index.html
http://www.elcorteingles.es/
Maybe worth using this site to compare the stores in Spain
http://www.ciao.es/Super_Sol__Opinion_543865
The attraction of Spain isn`t the cheap lifestyle anymore, those days I`m afraid are lost in time.
The same myth is that Spain is perfect, its not, in so much as some like it, some love it and some hate it.
I`ve had family from within Spain who hate where we live, I had family from the UK who love it.
Many make the mistake of viewing Spain as the same, its not, its a huge diverse country that culturally changes drastically from region to region.
Which makes it difficult to no the best place to start lookin for a home that will suit your needs.I`ve taken expat friends to visit my OH town in the north, they couldn`t believe the difference and never realised how much they prefered it.
The three best pieces of advice I could give before moving to Spain is :
1)Learn the language to at least basic conversational level
2)Learn the culture of Spain.
3)Research as many regions by visiting them as you can.