I reached the same conclusion, and I'm going to Spain for a week on Sunday! The flying hours are much more expensive in Spain than in the USA, but for 20ish hours of flying over a week or so, Spain works out a little cheaper and a lot more convenient.
Correct - It totally depends on how many hours your going to do.
It looks like these calculations that if you we're doing 0-PPL Florida would be the cheapest though if like me, you are going to need less hours then there isn't much in it (£2-300) between Spain and the US.
This obviously ignores the standard of instruction but you've got no way of guaranteeing a good standard of instruction wherever you go.
Best of luck in Spain - let me know how you get on.