yes, I was surprised too about the low price of some Hostels. As in my most recent trip down to Andalucia I stayed in a Hostel in Antequerra for 15 euros . it had Air-co, tv, own bathroom , firdge, double bed, secure bike parking ( in my room ) and right in the centre as opposed to the 13 euro campsite that was 5 miles out of town. I like camping when it's good but when the price goes over 10 euros it feels like i'm being taken for a ride( and not in the nice way i enjoy ).
The Albergues are good and out of season are often very quiet or empty.
I have booking dot com on my phone so i can look up what's in town but don't use it to book through. as in the case of the Antequera hostel i got it 5 euros cheaper by asking at reception than on line.
I also have Warmshower app on my phone which has been great.
There's also Air BnB which can be reasonable.
I've read a lot of blogs that mention just asking in a bar for a room. I've never done this but worth a try if you get stuck.
Although i use the Michelin paper maps I also use backcountry navigator which is about £7 for life (free year trial) and allows you to download maps offline. It only has one source of maps for Spain but it does show topography.
someone on the CTC forum pointed me in the direction of a great site called cycle travel :
http://cycle.travel/mapAs with google maps you can bung in the start and end point and it will calculate distance. one thing to remember with it though is that it can direct you down some more "off road" tracks which may not be what you're looking for.
it also shows campsites and hotels (you have to zoom in to see them)
Another app that is good is the bikehub app (for some reason my phone app works in Spain but my computer doesn't) :
http://routes.bikehub.co.uk/