Short of buying a car then selling it at the end of your trip, I would have thought your limited to the car rental companies.
You can get monthly deals with the car rental companies. Economic crisis and all that crap, try talking them into a better deal.
Something to be aware of. A year or so ago the car rental companies never provided high viz vests in the cars or spare bulb sets which are a legal requirement in any car on the roads in Spain or they would charge extra to have them included with a car.
Instant fine waiting to happen to anyone stopped by the police.
Please keep us informed if you find a cheaper way of doing things
