Hi Andy.
The most important book shop in Barcelona is L´Aeroteca, I know that they sell a lot of books regarding all kind of aviation…I don´t really know if they are expensive or not, because all bokks I have are coming from UK and US.
I reccomend you that for buy good books to take a look to US shops on ebay.
example:
I recently bought a good ( Spitfire V the manual ) in US. Very cheap !!!:eek:
It cost in UK something like GBP 40.- parcel included (new)
Mine´s costs to me 26 US $- parcel included (new)
If you are looking for good books in Spain, probably you are going to pay high prices due importation taxes, etc….
Hope it helps.
carleso123