Greece always used to be the cheapest option, however these are difficult times for them, and costs are rising.
We’ve been in Preveza, Ionian for some time and have been very happy with Preveza Marine (there is also Aktio Marine and Cleopatra yards next door). This is a lift out option rather than a Marina and it works very well.
They are very efficient, costs are lower than pontoon berthing, there is no risk to the yacht when you are away (it will not sink), they will launch at the time and date you request.
There can be a bit of hassle getting there, picking the best low cost flights, sometimes via Corfu or Athens. We take the view its all part of the getaway!