I know Spain pretty well having lived there for 2 years and then spending a couple of months a year there while living in BsAs. I'd recommend Cadiz, a great little city with a bit of everything. Great beaches, lovely old town, which is busy with people, big university, great market, plenty of good/reasonable places to eat, and really friendly people. You'll notice the difference from the Porteños. Good communications with airports at Jerez and Seville and buses go all over. I'm renting my 3 bed apartment for €420 a month, which is probably about the going rate. You can find somewhere smaller for much less. There's a great market for fish, meat and fruit/veg, and food prices are very reasonable, less than Barcelona for sure. Not much English spoken though, and their Spanish is pretty hard to get the hang of, they speak so fast. I love the place and go back every year even though I've emigrated to Australia now.
Second this, as Cadiz is 15 minutes up the road by car from us and the beaches are wonderful...ancient walls of a fascinating city to one side and blue blue sea to the next. Joe we chose Andalusia for many reasons:
1. Little English spoken so we could continue to live and improve our Spanish
2. Conservative & historic town (s) that have life all year (ie life not ruled by the coastal tourists even if the beaches are beautiful)
3. Countryside 20 mins by car for riding, hunting etc
4. Mountains 4 hours by car for skiing(Sierra Nevada)
5. Multitude of beaches at 20 - 30 mins by car (Cadiz, Chiclana, Puerto de Sta Maria are our regular haunts)
6. Proximity to airports (Seville, Jerez, Malaga)
7. Great international schools following UK Cambridge system
In our hunt for the new place to live we also spent time in Cordoba, Almeria, Valencia, Murcia, Alicante, Elche, Bilbao, Barcelona, Madrid, Granada, Ronda, Jaen and too many white villages to mention. There's a host of beautiful places to live in Spain untouched by the English speaking tourism. You need to visit.
Sorry I don't have details on shopping costs to hand but on age we spend 120-150euros per 10 days for supermarket shopping including meat, chicken, pork, lamb, wine and the rest for a family of 4. We buy fruit, veg, fish U& bread from the local market for 10-20 euros a week. Will aim to dig out a shopping receipt and post details for you to compare. For us food is cheaper here than Bsas but that's because we didn't live on lentils and sugar whilst in Bsas. For idea of rental possibilities across Soain see tucasa.es...but as mentioned before the prices are dropping every month so you can take the prices and consider them negotiable.