We have just come back from a week in Ljubljana and didn’t find it expensive. Coffee about €1, a beer €1.5. The apartment we rented was €75 a night. Public transport was cheap.You could get a three-course dinner for less than €10, and museums were €2 to get in. We even attended a magnificent concert by the Student Philharmonic Orchestra for free.
OK, I take it back, then - trust me to base my experience from random pub chatter. Probably was a stag do attendee who got screwed, and not in the appropriate way.
I found Spain to be stuffed to the gills with what my North American ass regards as ridiculously cheap hotels – not flophouses, either; not fancy but decent, locks on the doors, clean washrooms, all that good stuff. I never spent more than €25 a night the whole two months. And their trains and buses all seem to be ridiculously cheap as well. I was last there late August through mid-October. That would definitely be my suggestion, out of my limited experience.