Canīt comment on Greece at all but Iīm in spain right at the mo on a mini road trip and itīs pretty damn good.
No probs at all doing it on the cheap. Even fuel is about half price compared to neighboring France. If you can get yourself a van then it seems common to join the crowd living in parking lots.
Climbing wise thereīs a lot of variety. Definitely is a lot at the harder end of the spectrum (canīt comment on that) but also lots for the more average climber too.